Our guide to what to look out for on Wimbledon's Manic Monday.
Maria Sharapova (SRB)  vs. Sabine Lisicki (GER) : These two ladies just can't help coming up against each other on the big stages. For the third time in the last five Slams, Sharapova and Lisicki will clash in a rematch of last year's semi-final, which Sharapova won 6-4, 6-3. Their matches are all about power, with Lisicki owning one of the biggest serves and forehands in women's tennis, and Sharapova hitting consistently and flat off the ground. The German is still trying to find her best form here at Wimbledon, after an ankle injury in April interrupted her season, though her return to grass has helped restore her confidence. Unfortunately for Lisicki, even at her best she has yet to be able to beat Sharapova, and the Russian's ruthless hitting should be enough today.
Pick: Sharapova in two sets.
Ana Ivanovic (SRB)  vs. Victoria Azarenka (BLR) : No woman is flying more under the radar this year than world No. 2 Azarenka. She has not dropped a set in her first three rounds and she's been keeping a low profile in the lead-up to the tournament. Ivanovic on the other hand has needed all three sets in all three matches to get here. Given Ana's inconsistencies, it's hard to bet on her to beat Vika here, but we know she has the tennis in her to do it if she can hold her nerve.
Pick: Azarenka in two sets.
Did you know... If Azarenka beats Ivanovic, and Sharapova and Radwanska lose today, Azarenka returns to No. 1.
David Ferrer (ESP)  vs. Juan Martin Del Potro (ARG) : Lots on the line here, obviously, but one notable fact: both David and Juan are looking to make the quarter-finals of Wimbledon for the first time and thereby complete a set of Grand Slam quarter-final appearances. Whoever wins will be the 40th man in the Open Era to reach the last eight at all four Slams. Was that too much tennis nerdery? Sorry. But here's another stat you can use: Ferrer holds a 4-2 record against DelPo, and he beat him in their only meeting on grass in 2008. Relevant, no?
Pick: Ferrer in four sets.
Did you know... Ferrer leads the tour in match-wins this year with 46.
Novak Djokovic (SRB)  vs. Viktor Troicki (SRB): Want to noodle on a bit of "what iffery"? Djokovic was mired in a slump in 2010 when he faced off against his countryman in the first round of the U.S. Open. Troicki found himself up two sets to one and a break up at 3-1 in the fourth, a mere three games from victory. As we all know, Djokovic survived to win the match, went on to save match points against Roger Federer in the semi-final, and then lose to Rafael Nadal in the final. But that tournament gave Novak a lot of confidence, and we all know what he was able to do in 2011.
Pick: Djokovic in three sets.
Did you know... Troicki has lost to Djokovic 11-straight times. Hence my pick.
Marin Cilic (CRO)  vs. Andy Murray (GBR) : Another day, another tough match for Mr. Murray. Have both these men recovered from their emotionally (and physically) draining third round matches on Saturday? Murray raced the clock and overcame some slipping and sliding to beat Marcos Baghdatis in four sets, while Cilic almost blew a two sets to love lead over Sam Querrey, finally winning the match 17-15 in the fifth. In their only grass court meeting, Murray defeated Cilic in a Davis Cup tie in 2007, and since then he's only lost to the Croat once.
Pick: Murray in four sets.
Did you know... Andy Murray is bidding to become the first British man since Fred Perry - OK, I'll stop. Of course you know. We all know.
Five more to watch (because they don't call it Manic Monday for nothing):
Roger Federer (SUI)  vs. Xavier Malisse (BEL): Oldies but goodies: Fed and X-Man are the two oldest men in the Round of 16.
Serena Williams (USA)  vs. Yaroslava Shvedova (KAZ): Shvedova won 24 straight points to win the first "Golden Set" at a Slam on Saturday. Pretty sure that's not going to happen today.
Kim Clijsters vs. Angelique Kerber (GER) : Here's the first big test for Clijsters, who will take on the winningest player on the women's tour this year. I've asked it all week and I'll do it again: Will this be Kim's final match at Wimbledon?
Jo-Wilfried Tsonga (FRA)  vs. Mardy Fish (USA) : Fish has never beaten Tsonga, though they did have a tough five-set tussle at the U.S. Open last year.
Francesca Schiavone (ITA)  vs. Petra Kvitova (CZE) : Kvitova improved as the first week wore on, while Schiavone seems to have found her flamboyant attacking style on grass. But I'm not sure the Italian will have any answers for Kvitova's pure power.