Federer sets up last eight encounter with Del Potro

Roger Federer continued his ominous march toward a third Grand Slam title of the year at the US Open on Monday, beating Germany’s Philipp Kohlschreiber in straight sets to move into the last eight.

Federer will face Argentina’s Juan Martin del Potro in the quarter-finals.

The 36-year old Swiss was once again just too strong for his opponent, not dropping his serve as he handed the German a 12th defeat in 12 meetings.

The opening six games went with serve before Federer earned the first break to take a 4-3 lead, from where he served out for the set.

A horrendous missed volley from Kohlschreiber then handed the 19-time Grand Slam champ a break for 2-0 in the second set, and he didn’t waste it, closing out the set with little trouble for a two-set lead.

Federer then disappeared off court for a massage, once again raising questions about a recent back injury that seemed to affect him in earlier rounds.

The break didn’t seem to affect Federer too much though, as he proceeded to apply constant pressure on the German’s serve, finally getting the crucial break to lead 6-5.

The rest was a formality as he cruised into the last eight and ever closer to a semi-final meeting with nemesis Rafael Nadal.

In the earlier match, del Potro staged a superb comeback, fighting off illness and saving two match points as he beat Dominic Thiem in five sets.

The 2009 champion struggled with illness early on and called for the trainer in the opening set, but rallied to win a titanic battle 1-6 2-6 6-1 7-6 (7-1) 6-4.

“I was sick the last two days and I came here to play as best as I can. I was trying to feel better after a few games – I fight like this because of you guys,” Del Potro said in his post-match interview.

“I am so happy I came through, playing this great match. Maybe I will have the chance to play Roger again in this tournament, which is special for me.”

Sixth seed Thiem, 24, broke Del Potro in the very first game as the Argentine seemed to be struggling with his vision.

The Austrian raced through the first set in 36 minutes and gave up just two games as he took the second.

Del Potro then seemed to get a boost with the crowd behind him and perhaps the medication as he broke Thiem in the second game and went on to take the set after another break.

The 24th seed then needed to save two match points at 6-5 in the fourth set, serving up aces on both occasions to hold serve, before winning the tiebreak to take the match into a deciding set.

And the Argentine completed the most unlikeliest of comebacks after more than three hours out on court when a Thiem double fault handed him the fifth set and the match.