MELBOURNE, Australia (AP) It's the start of quarterfinals at the Australian Open on Tuesday, and none of the other three will likely be as compelling as the one between Roger Federer and Mischa Zverev.
Federer has 17 Grand Slam singles titles but is playing in his first official tournament in six months after a left knee injury layoff. The 50th-ranked Zverev had a four-set upset victory over top-ranked Andy Murray in the fourth round, a result the 29-year-old lefthander called the best of his career during his post-match media conference .
The 35-year-old Federer looked flawless in beating Tomas Berdych in the third round and then defeated fifth-seeded Kei Nishikori in the fourth round in five tough sets.
''It's going to be completely different to the last couple, it's probably going to be more similar to (Jurgen) Melzer in the first round, which is good that I played him,'' Federer said. ''I have a lefty in me this tournament already. I'm going to practice with a lefty as well again, just to get ready for that.''
Federer, who has beaten Zverev twice in two meetings - the first was on clay in 2009 and the second at Halle on grass in 2013 (6-0, 6-0) - figures it will be a whole new Zverev across the net at Rod Laver Arena on Tuesday night.
''Obviously he's on a high right now. He's feeling great. Probably feels the best he's ever felt on a tennis court,'' said Federer.
Here is a look at the other quarterfinals on Tuesday:
NO. 7 GARBINE MUGURUZA VS. COCO VANDEWEGHE
French Open champion Muguruza lost to Vandeweghe twice on grass in 2014, once in a qualifying tournament and then in first round at Wimbledon (in three sets). But Muguruza beat the American in the second round at Cincinnati on hard courts last year in straight sets.
Vandeweghe is coming off a huge upset win over No.1-ranked and defending champion Angelique Kerber in the fourth round. The American described her match against Muguruza as ''an interesting matchup.''
''She holds a different aspect to a playing style of she's an aggressor, as well,'' Vandeweghe said. ''She is going to play that way, and no other way. For me it depends on if I can match it, as well as if I can beat her to that punch of getting first strike, first play. She's a tricky player. She has a lot of power, full shots, serve, everything.''
NO. 4 STAN WAWRINKA VS. NO. 12 JO-WILFRIED TSONGA
This should be a close one, and a long one. Wawrinka has won four of seven matches against Tsonga. Their only previous meetings in the majors were three matches at the French Open. The last time was in 2015, when Wawrinka won a semifinal in four sets, including two tiebreakers. Before that Tsonga beat Wawrinka in five sets at Roland Garros in 2012, and Wawrinka needed five to beat Tsonga there the previous year.
''I know he's playing really good,'' Tsonga said. ''It's going to be important for me to be good in this match and play my best level.''
Tsonga was at his near-best in 2008 here when he lost the final to Novak Djokovic. Wawrinka, who won last year's U.S. Open, collected the first of his now three Grand Slam singles trophies at Melbourne Park in 2014.
Tsonga wasn't too upset to see Murray beaten in the fourth round: ''For sure it's better for me if I don't have to play Andy because I have a bad record against him,'' he said, smiling.
NO. 13 VENUS WILLIAMS VS. NO. 24 ANASTASIA PAVLYUCHENKOVA
Williams holds a 3-2 career edge in head-to-head matches, but Williams won the most recent match_on hardcourts in three sets at Montreal in 2014.
''I know her game, I have played a lot of matches this tournament kind of not knowing what to expect,'' said Williams. ''Now I have played her, I know what to expect. So I can almost already be settled in before I get to that match. So it's a good thing.''
Williams has not dropped a set in four matches this tournament, and her sister, Serena, is impressed.
''I think she's playing really well,'' Serena said. ''She's been really putting in a lot of the hard work. She had a really intense preseason.''
Pavlyuchenkova's appearance in the final eight here completes a set of quarterfinal appearances at all four Grand Slams, although she has failed to get past that point.
''I was always wondering why I could never have a good start here in Australia after good preseason, good offseason, and a lot of practicing,'' she said. ''But now it seems like I found a way.''
Their match will start proceedings on Rod Laver Arena.