Some really special tennis off Federer's racquet today.He goes high for a jumping forehand shot and Melzer doesn't know what to do with it! Game Federer, who leads 4-1 in the second.
Federer's bringing out aces like he's playing poker today! After an aggressive push back from Melzer with some great forehand winners, Federer - who has nineteen aces so far - has Melzer's back to the wall. He leads 3-1.
Three aces from Roger Federer to start off the fourth set. Melzer's left completely flummoxed and swatting in the air for a shot that's already made it to the other end.
What a STUNNING down-the-line forehand from Roger Federer. Arguably the best point of the match from Roger Federer, who's leading 5 games to 2. Melzer serves to stay in the set.
Federer leads 3-1 in the third set, but it's not been all smooth sailing for the Swiss. A couple of backhands have been a bit sloppy, but he takes it home in the end.
Scores are level at 1 game all. Federer combats a good baseline shot from Melzer but sends it unfortunately right into the bottom of the net. Not the placement he was looking for..
A 31-minute second set goes the way of Jurgen Melzer, 6-3. It's not as one-sided as it seems, though, with Federer hitting 5 aces. Not an ideal winners to unforced error ratio for the Swiss though, with 11:13.
Federer tries a long, heavy combination of shots to get through there, but nets it in the end. Melzer holds for 2-3, and now breaks Federer to level at 3 games all.
Credit to Jurgen Melzer - he has not looked tired just yet, although he's lost control a fair bit now. He manages to hold on to his service game for the first time in the second set to trail 1-3.
Easy does it! Don't be caught napping or you'll have missed that absolutely lightning-fast game from Roger Federer. He holds to love for three set points and WINS the first set 7-5!
And Melzer is struggling to get his returns to Federer's volleys just right. As before, he nets that one. Roger Federer holds to love! He equalises at 5 games all.
And there's the crucial break back! After some back and forth and some scrappy tennis from both players, Federer engages Melzer in a quick rally. It ends with Melzer, who's trying to match Federer shot for shot, netting that forehand.
Federer runs away to deuce after Melzer nets a crucial couple of shots. A shot from Federer goes long, and the chair umpire asks to challenge. It's at game point too, with Melzer at the advantage. It's out. Point, and game Melzer. He leads 3-2 on serve.
And Federer declares himself straightaway! Some exquisite backhands from the Swiss straight down the line and he almost holds to love. But it's not to be. 40-15, and he holds for 2 games all.
Stan Wawrinka, US Open 2016 champion, isn't having the dream run he'd have liked yet. After losing the first set, he wins the second 6-4, sees a scare from Klizan to win the third 7-5, and now Wawrinka will hope to seal it in the fourth. He's level at 3-3.