Who are the toughest players to guard in college basketball?

Azubuike maneuvers around defense for the bucket (0:18)

Udoka Azubuike grabs the pass, goes around the defender and crushes the two-handed slam. (0:18)

Unlike last season, college basketball lacks a superstar this season. But the field is stacked with elite players who have caused headaches for opposing head coaches.

More than 20 Division I coaches, when asked by ESPN.com, pointed to the following players and the problems they present as the most difficult matchups in college basketball.

This isn't a definitive list. There are many players who have been hard to stop. But these are the names that were frequently mentioned by the coaches who have had to scheme to limit these players' production in the 2019-2020 season.

Obi Toppin's spot-up jumper, drive option after he slips a screen: Toppin is a handful at 6-foot-9, 220 pounds. The coaches who have been asked to defend him say he's a difficult matchup because he's too athletic for most power forwards and centers to defend, and he's too strong and big for guards and small forwards. But they also point to his ability to slip ball screens as one of his most dangerous maneuvers because he's such a potent inside-outside threat. You can see it on the film. On the second possession of Dayton's win over Saint Mary's this season, Toppin flies into the play to set a screen on Jordan Ford as Rodney Chatman dribbles up the court. After Chatman drives hard to the rim, Toppin slips to the top of the key and waits for Chatman's pass. Saint Mary's immediately recognizes the problem, as five defenders who had mobilized to stop Chatman at the rim have given Toppin a clear path to the basket for a simple drive or plenty of room for an uncontested jump shot. Toppin, who has made 44.3% of his jump shots inside the arc (hoop-math.com), picked the latter and made the shot.

Division I head coach who has faced Toppin: "It's hard to switch ball screens because he can post. And he's hard to guard with a big on the perimeter."

Division I assistant who has faced Toppin: "He can score at all levels. Good shooter, and he's super athletic. Loves to score off his freaky athletic ability: transitions, trailer 3s, slipping ball screens or rolling to the basket. We thought putting a smaller guy under him and switching 5 was the best way to guard him."

Udoka Azubuike's dunks, easy layups after he seals his defender with his massive forearm: It's almost unfair to put the Kansas center on the same court as other college kids. The 290-pound 7-footer has made 77% of his shots inside the arc, most of those within a few feet from the basket. His sheer strength is his greatest asset. How he uses it for favorable positioning, however, is undervalued. While matched up against Toppin five minutes into the second half of a 90-84 win over Dayton in November's Maui Invitational championship game, Azubuike nudged the Dayton star with his left forearm, causing him to briefly lose his balance. That gave Ochai Agbaji enough time to toss a pass to Azubuike, who finished with an easy dunk. It's a difficult move to stop because officials are more likely to see a defender tussling with Azubuike -- and call a foul -- than the initial nudge. Once he's near the rim, it's an automatic bucket for Azubuike.

Division I head coach who has faced Azubuike: "He is bigger than all the planets in the universe. No way to guard him. You can try to foul him, and he still dunks your entire team in the basket."

Collin Gillespie's step-back jumpers and drives off his spin move: In a loss to Baylor on Nov. 24, the Villanova guard spun left while matched up against Jared Butler and sped to the rim for a pretty layup that dropped over Tristan Clark's fingers late in the second half. The 6-foot-3 guard is an excellent scorer who has connected on 46% of his shots inside the arc and 38% of his 3-pointers. He has also been an excellent scorer when he has found ways to get into the lane (59.1% clip at the rim, per hoop-math.com). The spin move -- maneuvers off high ball screens and dribble handoffs, too -- allows him to create separation and use his speed to get a step on any opposing defender. As a result, good teams in college basketball have called him one of their greatest matchup challenges this season.

Division I head coach who has faced Gillespie: "He had the best game against us. You can't speed him up. Can't take him out of their stuff. He's shifty. He gets to spots when he wants. And he makes shots."

Markus Howard's quick shots off screens: Based on the numbers, it's easy to assume that Howard is an unstoppable force by himself. But his teammates do a lot of work to keep him in motion, constantly searching for a shot. It's like watching the Kansas City Chiefs block for Tyreek Hill, waiting for the explosive runner to break free. When Howard's teammates contribute to his offensive exploits, one of the nation's best offensive players (43.1% from the 3-point line, 58.3% on spot-up jumpers) becomes an impossible force. During the first half of his 42-point effort in Saturday's 84-80 win over Georgetown, Koby McEwen waited at the top of the arc as Howard sprinted from the left wing, through a trio of screens underneath the basket and over to the right wing, where he nailed a 3-pointer. Georgetown's Terrell Allen looked like a pinball as tried to fight off three screens. But he remained a step behind the smooth Marquette star. And if teams are too aggressive, they put an 85% free throw shooter on the line.

Division I head coach who faced Howard: "His ability to move and shoot keeps you off-balance. Then his ability to get to the free throw line is hard to contain."

Myles Powell attacking the basket in isolation scenarios: Powell has emerged as a certain All-American in 2019-20 while also securing a shot at the next level after averaging 22.4 PPG and connecting on 38% of his shots from beyond the arc and 81.3% of his free throw attempts. Coaches who have been charged with stopping him have pointed to his diversified game and ability to score in traffic as crucial weapons. Once he gets downhill, he's very James Harden-like in his tendency to draw contact or make tough shots in the paint. In the second half of his 29-point outing in Seton Hall's 82-79 victory at St. John's on Saturday, Powell was the ball handler as Nick Rutherford shadowed him. On that possession, Powell scored after he switched from a deceptive, patient dribble to a quick burst toward the rim as Rutherford trailed him. He's strong and difficult to defend when he turns on his motor in sequences such as that, per the coaches who have dealt with him. He's also unpredictable.

Division I head coach who has faced Powell: "He plays off his shots very well. Every shot he takes has a chance to go in. He knows angles, and he can play a defender against himself. He's much improved."

Another Division I head coach who has faced Powell: "He's a four-year guy. He has strength and toughness. He's just a tough son of a b----, and he can shoot it from anywhere. He can make it from anywhere."

Anthony Edwards in transition: Georgia's star is a projected top-three pick in the upcoming NBA draft on every meaningful mock board. He's a special player who has an NBA-ready, 6-foot-5, 225-pound frame. He isn't built like most players at the collegiate level, and he has the potential to mature into a more efficient offensive player at the next level. But he could make an immediate impact now. Those who have encountered Edwards say he's a handful everywhere, but especially in transition, where he's listed as "excellent" on Synergy Sports after making 62.1% of his shots in transition thus far. When he's racing up the floor, it's a helpless moment for collegiate defenders. In his team's 80-63 win over Tennessee, the Vols scored with 1:39 remaining in the first half. Five seconds later, Edwards flushed a fancy dunk after taking an outlet pass from Sahvir Wheeler and dribbling around Santiago Vescovi on the other end of the floor. He's just that explosive.

Division I head coach who has faced Edwards: "He stays in attack mode. He's bigger, faster, stronger than everyone at his position."

Jared Butler dribbling into spot-up jump shots: Although No. 1 Baylor has been touted for its defense, the team is also blessed with talented offensive players. For that reason, Butler might be the most important player on the team. With him on the floor, the Bears have averaged 109 points per 100 possessions. With him on the bench, the team has averaged just 96 points per 100 possessions. Why? Multiple coaches who have been charged with guarding him say he's hard to corral because of his ballhandling skills and shooting ability (40.2% from the 3-point line). If you check the tape, you'll find multiple examples of Butler in a tight spot before using his fluid ballhandling to control the situation. On the first possession of his team's win over Maryland Eastern Shore earlier this season, Butler passed on a 3-pointer on the left wing as Maryland Eastern-Shore's Ahmad Frost closed in. Then Butler took a step toward the basket before quickly dribbling into a step-back 3-pointer. Those are the sequences that have kept opposing coaches up at night.

Division I head coach who has faced Butler: "On tape when we saw him, I thought he was a good player. After playing him and watching him, he is really good. He plays at a great pace and under control. He doesn't force the issue. He can score in a variety of ways."

Another Division I head coach who has faced Butler: "He can score off catch-and-bounce plays. His handle is so tight that he's hard to pressure. And he's a great shooter."

A third Division I head coach who has faced Butler: "He has really good ball skills. He shoots it well. He can really get by you. He's also surrounded by a really good core, so that helps him to have a lot of space to create."

Isaiah Stewart in the post when teams fail to keep a body on him: Washington began the season with a win over a Baylor team that now sits atop the rankings. But the Huskies are off to a 2-4 start in Pac-12 play. Still, at least one head coach of a top program called Stewart the most difficult player his team has met this season. The 6-foot-9, 250-pound freshman is mobile and athletic. Combine that with his power, and he's a mismatch for most opponents. In Saturday's 64-61 overtime loss to Oregon, he finished with 25 points and 19 rebounds. Oregon had trouble staying in front of him, a constant challenge for teams that have played Washington this season. Early in Saturday's game, Oregon's N'Faly Dante tried to put himself between Stewart and the rim as Marcus Tsohonis released a shot from the corner. It didn't work. Stewart wouldn't budge. He spun off Dante, found space and finished with a putback on the other side of the rim. Dante seemed perplexed by the sequence. With Stewart in the paint, Washington is the No. 2 offensive rebounding team in the conference.

Division I head coach who faced Isaiah Stewart: "He required double-teams. And I was very impressed with his hands, his touch [around the basket] and his motor."