So far, two of the favorites for the national title have had to win games without their point guard.
UCLA beat Michigan State and Maryland sans Darren Collison.
North Carolina outlasted BYU and pulled away from Ohio State without Ty Lawson.
Collison played in his first game earlier this week, against George Washington. Lawson said Wednesday he expected to return Saturday against Kentucky, but coach Roy Williams said Friday that he is "skeptical" of Lawson's availability for the game.
Collison and Lawson are two of the highest profile injuries so far. But there have been plenty of others on the IR.
Here are some key updates:
Ryan Appleby, 6-2, senior, Washington
Appleby is out with a right thumb injury. The hope is that he could return as early as Saturday at Oklahoma State or next week against Pitt in Seattle. The Huskies are desperate for his perimeter shooting. Appleby averaged 10.5 points a game last season and made 43.3 percent of his 3s.
Sherron Collins, 5-11, sophomore, Kansas
Averages: 16.0 ppg, 3.5 rpg and 5.0 apg in two games
Collins is out with a broken foot. The hope is that he can return by mid-December. Even though Kansas has played four games without him, Collins is still the team's leading scorer. KU coach Bill Self said that as soon as Collins comes back, the Jayhawks have a shot to be a really good team. They're already an elite squad, and having Collins next to a healthy Brandon Rush should make them even more productive.
Sharaud Curry, 5-10, junior, Providence
Curry hasn't played this season because of a broken foot. He averaged 15.3 points and 4.4 assists a game last season. Once Curry returns, the Friars will have a legitimate shot to be an NCAA Tournament bubble team. He gives Providence a breakdown point guard who can create for others.
Mamadou Diarra, 6-11, freshman, USC
Diarra had hernia surgery in the preseason. The hope is that he can join the team in January. Diarra would give the Trojans another shot-blocker and rebounder, although it likely would take him a while to get up to speed.
Steven Gray, 6-4, freshman, Gonzaga
Gray broke his wrist and likely is out for a few more weeks. Gonzaga coach Mark Few said Gray was one of the team's top perimeter shooters. If he returns in form, the Bulldogs will be even more potent offensively.
Josh Heytvelt, 6-11, junior, Gonzaga
Heytvelt has yet to play this season because of a broken foot. The hope is that he'll return sometime in December. Once he does, the Bulldogs will have one of the premier frontcourt scorers in the west back in the lineup. Heytvelt averaged 15.5 points and 7.7 rebounds in 25 games last season.
Derrick Jasper, 6-6, sophomore, Kentucky
Jasper is still out after microfracture surgery on his knee in the offseason. Kentucky coach Billy Gillispie said recently that Jasper is the team's top playmaker. So, getting Jasper back soon would be a boon to this squad. But that might not happen for a few more weeks. Jasper averaged 3.9 points and 2.9 assists last season.
Gary Johnson, 6-7, freshman, Texas
Johnson hasn't played yet, reportedly because of an undisclosed heart condition. After being held out of summer workouts, the forward has been practicing but has not been cleared to play in regular games. He did compete in one exhibition game and had 13 points, six rebounds and two blocks in 19 minutes. Once he returns, the Longhorns should have the necessary rebounder, screener and presence in the post to make a potential Final Four run.
James Keefe, 6-8, sophomore, UCLA
Keefe had offseason surgery on his left shoulder, and he said recently that he's hoping for a late December return. Keefe is another face-the-basket forward who could help cause defensive matchup problems. He made 3 of 9 3s last season in limited minutes. He probably won't get too many when he returns, but having him as a reserve could give Ben Howland more options up front.
Ty Lawson, 5-11, sophomore, North Carolina
Averages: 10.6 ppg and 4.6 apg in five games
Lawson missed the last game-plus with a sprained right ankle. The Tar Heels beat BYU with Lawson playing only two minutes, then beat Ohio State without him. Lawson is UNC's Energizer bunny. He's as quick as anyone in the country, maybe the quickest point guard next to UCLA's Darren Collison. Lawson said after the Ohio State game that he should be back to play at Kentucky on Saturday (ESPN2, 2 p.m.). The Heels need him on the court to have a shot at the title.
James Mays, 6-9, senior, Clemson
14.8 ppg and 8.6 rpg in five games
Mays suffered an injured hip against Gardner-Webb on Saturday. It was first feared to be fractured, but is just a strain. The Tigers beat Purdue in the Big Ten/ACC Challenge without Mays. They play South Carolina on Saturday. The selection committee will watch to see how Clemson does without its top inside threat.
Jack McClinton, 6-1, junior, Miami
Averages: 14.3 ppg and 2.5 apg in four games
The Hurricanes' leading scorer missed the past two games -- wins over Morgan State and Alabama State -- with a thumb injury on his non-shooting hand. The hope is that McClinton will be back for the Canes' game against St. John's on Sunday. Clearly, the Canes simply survived in his absence (winning by four over Morgan State) and can't be expected to stay afloat in the ACC without him.
Jodie Meeks, 6-4, sophomore, Kentucky
Meeks is out for a few more weeks with a stress fracture in his pelvis. Meeks averaged seven points and 2.5 rebounds in his first two games before suffering the injury. The injury-riddled Wildcats need Meeks back ASAP to help offer some depth and more experience to the backcourt.
David Padgett, 6-11, senior, Louisville
Averages: 9.5 ppg and 3.5 rpg in two games
Padgett has played in two of the Cardinals' five games. He suffered a fractured kneecap against Jackson State, and the original report said he was done for the season. But the Louisville-Courier Journal reported Thursday that Padgett said he would possibly return by late January. If that were the case, it would rule out trying to get a medical redshirt for a sixth season of eligibility. Padgett is the Cardinals' leader and maybe one of the most dedicated to Rick Pitino's system. So, the loss of Padgett was a blow to the Cardinals' chances. If he can return and help lead this team, that surely aids Louisville's goal of getting to San Antonio.
Juan Palacios, 6-8, senior, Louisville
Palacios hasn't played yet this season because of a knee injury. The hope is that he'll return in mid-December. If he does, that will give the Cardinals a much-needed boost in the post, especially in light of Padgett's injury. Palacios' points dipped from 10.2 as a sophomore to 8.9 points as a junior last season, and his rebounds also slid -- from 6.3 and 5.5. Still, Palacios is a talent who can work the offensive glass and be a potential shot-blocker.
Michael Roll, 6-5, junior, UCLA
Roll is out with a ruptured plantar fascia in his left foot. He's close to returning. Once he does, the Bruins will get back one of their top perimeter threats. Roll made 35.8 percent of his 3s last season. He averaged just 4.9 points a game, but his presence can help stretch the defense.
Marcus Simmons, 6-5, freshman, USC
Simmons has been battling a high ankle sprain. He played in only two games for a total of 11 minutes. Once Simmons is healthy, the Trojans get a physical blocker and screener off the bench to benefit a team that is becoming tougher by the game.
Ronald Steele, 6-3, senior, Alabama
Steele is sitting out the season to rest his ailing knees. He has had multiple surgeries, and the decision was made to shelve him for the season. Steele averaged 8.6 points and 4.0 assists last season while battling knee injuries. His best season was as a sophomore when he averaged 14.3 points and 4.3 assists. Clearly, the Tide are an SEC West title contender with Steele in the lineup. Without him, they will need to scratch and claw to be in the bubble picture.
Adrian Thomas, 6-7, sophomore, Miami
Averages: 4.5 ppg and 2.3 rpg in four games
Thomas played in four games before tearing a ligament in his left knee. Thomas, who will miss the rest of the season, was a reserve guard who added depth for the Hurricanes.
Jamual Warren, 6-2, senior, Cincinnati
Warren is out with a hand injury suffered in a car accident. The hope is that he'll return within a week. Not having him clearly is having an effect on the Bearcats, who lost to Belmont and Bowling Green at home. He averaged 8.0 points and 3.2 assists last season. Warren is considered the team's top perimeter defender.
Mike Williams, 6-7, junior, Cincinnati
Williams is a transfer from Texas who was supposed to be Cincinnati's best player, but he ruptured his Achilles before the season and will miss the entire season. The Bearcats have struggled in his absence.
Andy Katz is a senior writer at ESPN.com.