W2W4 at Australian Open: Why Rafael Nadal should be leery of his next foe

Just like that, we're into the quarterfinals of the Australian Open. Only eight men and eight women remain. There are a handful of new faces as well as some old reliables. Here's what will be on tap on Day 9 Down Under:

No. 1 seed Rafael Nadal vs. No. 6 seed Marin Cilic (Nadal leads series, 5-1)

Does anyone else get the sense that Nadal is on a mission? Although he bagged the prestigious year-end No. 1 ranking for 2017, Roger Federer's unexpected recovery from 3-1 down in the fifth set of the 2017 Australian Open final against Nadal set the tone for another year of unmitigated Federer worship.

In the big picture, that puts Cilic into the category of "stumbling block." However, the former US Open champion is determined to add another major title to his résumé and has been working strategies for accomplishing that. Not to worry, Nadal fans: Your hero is too much the humble, respectful pro to overlook the damage that the rangy, raw-boned Croatian can wreak.

Cilic has tweaked his service action, and the net result, according to the man himself, has been satisfying. He's also hit the 20-ace mark in three of his four matches at Melbourne Park as he looks to be a more aggressive player. "When I have the chance against really good defenders, I'm going more for my shots," Cilic told the media.

That's exactly what Federer did last year against Nadal, and the Spanish star hasn't forgotten it. Cilic, beware.

No. 3 seed Grigor Dimitrov vs. No. 50 Kyle Edmund (Dimitrov leads series 2-0)

As it turned out, Dimitrov has had to navigate the most menacing draw among the top four seeds. In his past two matches alone, he has scored wins over fast-rising Russian Andrey Rublev and No. 17 seed -- and home-court favorite -- Nick Kyrgios. What makes Dimitrov especially dangerous is that he wasn't playing anywhere near his best, until now that is.

"I learned that I can switch to another gear when I really need it," Dimitrov told the media after he dumped Kyrgios out of the tournament. "The first couple of rounds, or even the three first rounds, I was not striking the ball well."

Dimitrov is approaching 27, with the task of winning a Grand Slam title fast becoming a "now or never" proposition. Edmund, a South-African born British player is just 23 and in his first Grand Slam quarterfinal, a journey that began with a quality upset of No. 11 seed Kevin Anderson. Dimitrov been a diligent, utterly dedicated pro -- something that couldn't always be said for the young Dimitrov -- who now seems on the cusp of a breakthrough.

Edmund is 6-foot-2. His bread-and-butter power game is anchored in a bone-jarring serve and a harsh forehand. Dimitrov also generates plenty of power, but he has the edge in versatility and touch despite being an inch taller. Their two previous meetings took place within the past six months, one just weeks ago in Brisbane. Dimitrov won both, but they were close three-setters. Edmund rolled his ankle in their Brisbane encounter, making life a little easier for the Bulgarian.

No. 2 seed Caroline Wozniacki vs. No. 39 Carla Suarez Navarro (Wozniacki leads, 5-2)

Can anyone stop Wozniacki? That's a fair question, given what a juggernaut the 27-year-old Dane has become over the course of the past 12 months. The next player tasked with the assignment is the game 5-foot-4 Canary Islander who has survived -- and prospered -- on the WTA tour the hard way: with a one-handed backhand, the frequent use of slice and a willingness to try aggressive approach shots as well as risky volleys and drop shots.

Wozniacki has lost just 10 games since that shaky second-round performance against Jana Fett, who had two match points when she served at 5-1, 40-15 in the third set. Since her miraculous recovery in that match, Wozniacki has been a dominant force, particularly in her fourth-round 6-3, 6-0 blowout of Magdalena Rybarikova. Wozniacki is on fire and has been for a year, leading the tour in 2017 in both wins (60) and top-10 finishes (14-5).

Suarez Navarro is on the upswing after a tough few months. She came to Melbourne toting a six-match losing streak dating back to the US Open. Ranked as high as No. 6 in the early part of 2016, Suarez Navarro had trouble holding on to her privileged place. It was partly because it's difficult to sustain an attacking mentality in a game where everything from the strings to the court surface to the balls and even stroking technique favors the rally game.

Suarez Navarro knows she will need to force the action and hit winners if she hopes to beat the superb defender and counter-puncher, Wozniacki. "My team, all the time they will say [to] me, 'Play aggressive, play aggressive,'" Suarez Navarro told the media in Melbourne. "But sometimes you cannot."

Upset Special: No. 36 Elise Mertens over No. 4 Elina Svitolina

Both women head into the clash riding nine-match winning streaks, including tournament wins in Australian Open tune-up events. The pressure is on high-seed Svitolina to prove she can contend at majors. Look for Mertens, 22, to seize the upset opportunity.