At the Net: Checking in on the Wimbledon contenders

Philadelphia, PA – As we head into the quarterfinals at Wimbledon, let's check in on the top contenders (and the no-longer contenders) for tennis' ultimate prize.

NOVAK DJOKOVIC

The high-flying Serb easily cruised into the quarterfinals, his 13th straight trip into a major quarter, which is the fourth-best streak in ATP history. Djokovic has been relatively untested at the 2012 fortnight as he seeks a second straight Wimbledon title. The Serbian stud has won four of the last six majors and has dropped only one match over his last five Grand Slam events. He sure looks like one of the best players in the history of the sport to me, and he has to be the best return-of-serve guy I've seen.

MARIA SHARAPOVA

The Russian bomber will not become the first woman since Serena Williams in 2002 to win both the French Open and Wimbledon in the same year after she was ousted by Sabine "Boom-Boom" Lisicki on the second Monday at the All England Lawn Tennis Club. The 2004 champion and 2011 Wimbledon runner-up had appeared in three of the last four women's major finals, but Lisicki kept her from trying to reach another by avenging a Wimbledon semifinal defeat at the hands of the Russian a year ago. Sharapova's No. 1 ranking could be in jeopardy this week.

RAFAEL NADAL

Tennis fans witnessed one of the biggest upsets in the sport's history last week when unheralded 100th-ranked Czech Lukas Rosol (who?) shocked the racquet god Nadal in a five-set stunner under the $80 million roof on the famed Centre Court at the venerable AELTC. The two-time Wimbledon champion had reached the final in his last five trips to the London suburb, including titles in 2008 and 2010. The 26-year-old Rosol was playing in the Wimbledon main draw for the first time in his career and promptly exited it in the next round (third round), losing to German Philipp Kohlschreiber. It marked Nadal's earliest loss at a major event since Luxembourg's Gilles Muller topped him in the second round at Wimbledon seven years ago. Nadal is an 11-time major champion who was fresh off his seventh French Open title in Paris a few weeks ago. He had appeared in the last five Grand Slam finals, winning two French Opens and losing to Djokovic at Wimbledon and the U.S. Open last year and the Aussie Open this year. Nadal defeated Djokovic in the French Open finale just 17 days before the Rosol mega-stunner.

VICTORIA AZARENKA

Azarenka has gone untested in the tournament, including a 6-1, 6-0 lambasting of fellow former world No. 1 Ana Ivanovic to reach the quarters. The Belarusian slugger reached her first-ever Grand Slam semifinal a year ago on the hallowed lawns. She is the reigning Aussie Open champ who wants to prove that this year's run in Oz was no fluke.

ROGER FEDERER

The six-time Wimbledon champ was slowed by a sore back in a fourth-round victory over Xavier Malisse, but he's still on course to meet Djokovic in the semis. Federer reached seven straight Wimbledon finals from 2003-09, but hasn't gotten past the quarterfinals since '09. His fourth-round victory at the Big W marked the 850th overall win of his remarkable career and sent him into a record 33rd straight Grand Slam quarterfinal. He's a walking tennis record book.

PETRA KVITOVA

The reigning Wimbledon champ is currently riding an 11-match winning streak at the AELTC and will appear in the quarters for a third straight year. She reached at least the semifinals at Wimbledon the previous two years and looks like a favorite to land in a second straight final in jolly old England.

ANDY MURRAY

Murray is still alive and hopes to give the Brits their first male Wimbledon champion in 76 years (Fred Perry, 1936). He's on course to reach a fourth straight Wimbledon semifinal, but would obviously prefer to reach his first- ever title match in the peaceful London suburb. Murray has reached three other major finals, going 0-3 and failing to win a set at a pair of Aussie finals (Federer and Djokovic) and a U.S. Open championship match (Federer).

SERENA WILLIAMS

Could still be the player to beat at SW19. Last year's U.S. Open runner-up has corralled four of her 13 major singles titles at Wimbledon, but was forced to play back-to-back tough three-setters in order to reach the quarters at the world's only grass-court Slam.

JO-WILFRIED TSONGA

Still kicking, he was battling American Mardy Fish for a spot in the quarters, with their fourth-round match to continue on Tuesday. Tsonga was a Wimbledon semifinalist last year and is a former Aussie Open runner-up.

ANGELIQUE KERBER

Dismissed outgoing Belgian Kim Clijsters to reach her first-ever Wimbledon QF. Kerber, who joins Kvitova as one of the top-two lefties in the women's game, was a surprise semifinalist at the U.S. Open last year, but has steadily climbed the WTA ladder since then, moving all the way up to No. 8 in the world after opening 2012 at No. 32. Clijsters was appearing in her final Wimbledon, as the three-time U.S. Open titlist will retire from tennis following this year's U.S. Open.

JUAN MARTIN DEL POTRO

"Delpo" doesn't typically play his best tennis on grass, but he's still in the mix at the Big W, where's he's never made it past the fourth round (at least not at the time of this column). The 6-foot-7 Argentine is a former U.S. Open champ who is extremely dangerous, of course, when his massive strokes are landing in.

SABINE LISICKI

The big-serving Lisicki is into at least the quarters at Wimby for a third straight time. "Boom-Boom" reached the semis last year and the quarters in 2009 before missing the 2010 edition due to injury. The sturdy German appears to have a real shot at winning it all this week.

MARDY FISH

Does he really have a chance? Coming off a heart procedure this spring, Fish is seeing his first tournament action since March and is vying for a spot in his second straight Wimbledon quarter. His big serve has been on over the first week and change at the AELTC.

TAMIRA PASZEK

Paszek is a perfect 8-0 on grass this year, including a title in Eastbourne two weeks ago. The once-promising Austrian has been living up to her promise of late, even if it's only been on grass. Paszek is now a back-to-back Wimbledon quarterfinalist and appears to have the perfectly suited grass-court game.

HONORABLE MENTION

Maria Kirilenko landed in her first-ever Wimbledon quarterfinal this week. The Russian beauty is perhaps best known as the girlfriend of NHL great Alexander Ovechkin. We'll call it "Beauty and the Beast."

Another Russian who landed in the quarters was Mikhail Youzhny, who had been 0-6 in his career fourth-round matches at Wimbledon ... until this week. The capable "Yuze" is a two-time U.S. Open semifinalist.

DISAPPOINTING AMERICANS

Five-time champion and three-time Wimbledon runner-up Venus Williams exited in straight sets in the first round against Russian Elena Vesnina, while 6-foot-9 John Isner succumbed to Colombian Alejandro Falla in five sets in the first round, and three-time runner-up (to Federer) Andy Roddick was a third-round loser at the hands of seventh-seeded Spanish grinder David Ferrer.

My picks to win -- Nadal and Sharapova -- well, let's just say, see you at the U.S. Open.