Federer and del Potro clashed in the Australian Open quarter-finals three years ago, when Federer dealt the Argentine his worst Grand Slam defeat with a 6-3, 6-0, 6-0 victory. Later that same year, though, del Potro edged Federer in a five-set epic in the US Open final.
"I think it's going to be a good match," said Federer. "Look, I think he's coming back awfully strong again. Injury came and things obviously changed, and now he's had to have a great year to get back in the Top 15, and now he's making his move to the Top 10. I think it's going to be a tough one. He really came through convincingly in the last two especially. We know the firepower."
The 30-year-old Federer advanced to the quarter-finals in Melbourne for the ninth straight year as he hit 45 winners to just 13 from Tomic, and broke serve six times from 10 opportunities. The last time Federer failed to reach the last eight of a major championship was at 2004 Roland Garros, when he lost to Gustavo Kuerten in the third round.
"I figured he was going to play a bit aggressive, that it was going to be a tough match, which it was, I thought," said Federer. "Maybe the score suggested differently, but I thought we had a lot of long games, tough points, and I thought he did actually really well."
The Swiss triumphed in Melbourne in 2004 (d. Safin), 2006 (d. Baghdatis), 2007 (d. Gonzalez) and 2010 (d. Murray). He also finished runner-up to Rafael Nadal in the 2009 final. He is bidding to win his 17th major title, and first since lifting the Australian Open crown in 2010.
Former World No. 4 Potro advanced to his first Grand Slam quarter-final since the 2009 US Open when he dismissed Germany's Philipp Kohlschreiber 6-4, 6-2, 6-1. "I can say I'm very happy to be in quarters," said del Potro. "It's amazing for me to play another quarter-final at a Grand Slam after three years, so it's good signal for my comeback.
"Roger is the best tennis player in history, and of course he's the favourite," added del Potro. "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 is going to be okay for me."
In defeating Kohlschreiber for the fifth time in five meetings, del Potro broke serve seven times and fired 31 winners to 14 unforced errors as he prevailed in two hours and six minutes on Margaret Court Arena. He has only dropped one set in four matches this week, winning 12 straight sets since losing the opener against Blaz Kavcic in the first round.
After winning his first Grand Slam championship at Flushing Meadows three years ago (d. Federer), del Potro was forced to miss the majority of the 2010 season after undergoing right wrist surgery. The 23 year old returned to action last year and earned the ATP World Tour Comeback Player of the Year Award, following his rise from a low of No. 485 in the South African Airways ATP Rankings to a year-end finish at No. 11.