Argentina's Juan Martin del Potro reached his first grand slam quarter-final in three years with a straight-sets win over German Philipp Kohlschreiber at the Australian Open on Sunday.
Del Potro defeated the unseeded German 6-4, 6-2, 6-1 to set up a rematch of his 2009 US Open final victory over Swiss third seed Roger Federer for his first grand slam title.
The towering Argentine 11th seed is fighting his way back up the rankings after career-threatening wrist surgery in 2010 and the signs are promising that he may again challenge to return to his best-ever ranking of four.
"I'm very happy to be in the quarters. It's amazing for me to play in another quarter-final in a grand slam for three years, it's a good sign for my comeback," he said.
"At last year's Wimbledon I had a very good match against Rafa (Rafael Nadal) in the fourth round, and I started to believe more in my game, on my serve, and then I closed the year almost in the top 10.
"So that's helped me to be ready for this year. Hopefully I will play healthy all this season and try to get in closer to the top guys."
Del Potro signalled his emergence as a top player with his upset five-set win over the then number one Federer at the US Open after overcoming Rafael Nadal in the semis.
Now he has gained his second quarter-final appearance at the Australian Open after losing in straight sets to Federer in 2009.
"Roger is the best tennis player of the history, and of course he's the favorite," he said.
"I remember three years ago I played in the quarters against him and I only won three games. So if this time is something different and I win more games it is going to be OK for me."
Federer greatly respects del Potro as his next opponent and is gearing for a tough struggle.
"I think he's coming back awfully strong again," Federer said. "I was sad to see that he was out for so long after his amazing year in 2009.
"I thought he had a chance in 2010 to sort of make a run for world number one before injury came and things obviously changed.
"Now he's had a great year to get back in the top 15 and now he's making his move to the top 10."
Del Potro was in command of his fourth-round match with the 41st-ranked Kohlscreiber, remaining unbeaten in their five meetings. He broke the German seven times and dropped his service once.