Del Potro back in the big time at last

Melbourne: Juan Martin Del Potro reached the quarter-finals of a grand slam for the first time since injury wrecked his 2010 season with a 6-4 6-2 6-1 victory over Philipp Kohlschreiber at the Australian Open on Sunday.

The former U.S. Open champion has been on the comeback trail since recovering from the wrist problem and took another major step with an emphatic win over the unseeded German in just over two hours on a sunbaked Margaret Court Arena.

The 23-year-old Argentine, who next meets Roger Federer, was ranked 236 in the world at the start of last season but resuscitated his career with titles at Delray Beach and Estoril and ended the year back on the brink of the top 10.

"I'm very happy to be in quarters... it's amazing for me play another quarters in a grand slam after three years, that's a good sign for my comeback," he said.

Quietly spoken and largely undemonstrative on court, the 11th seed's match against Kohlschreiber was the only main draw singles tie not played on the two main showcourts on Sunday.

The gentle giant started slowly in temperatures in the mid 30s Celcius before overpowering the neat and precise Kohlschreiber from the baseline with his clubbed groundstrokes and accurate returns.

Australian Open 2012

"The match today was difficult in the beginning because it was really hot and Philipp play difficult tennis for me," he said. "He made very good backhands down the line and playing the slices and serves and volleys.

"I closed the first set with my serve then took an advantage in the second and then my game started to feel more aggressive and confident."

Del Potro is almost certain to be back on the main Rod Laver Arena for his last eight meeting against four-times champion Federer, who he beat to win the U.S. Open in 2009.

Earlier that year, the 1.98m-tall former world number four suffered his worst grand slam defeat when he met the Swiss the last time he was in the Australian Open quarter-finals, losing 6-3 6-0 6-0.

"Roger is the best tennis player of all time and of course he's the favourite," he said. "I remember three years ago I played in the quarters against him and I only won three games.

"So if this time it's different and I win more games, it is going to be okay for me."