New York, Sep 5 (DPA) Andy Murray and Juan Del Potro fuelled ambitions as dangerous title contenders Friday at the US Open as both powered comfortably into the third round.

Second seed Murray, who lost the 2008 final to Roger Federer, the heavy favourite to lift a sixth straight title in New York, staked his claim on the third round with a defeat of Chile's Paul Capdeville 6-2, 3-6, 6-0, 6-2.

Argentine number six Del Potro dispatched Austrian Jurgen Melzer 7-6 (8-6), 6-3, 6-3, firing 13 aces and 36 winners to advance to his fifth victory without a defeat against the number 38.

The South American has fond memories of New York, where he reached a Grand Slam quarter-final for the first time 12 months ago.

'This is my favourite Grand Slam. I love to play here. I've started to play better on hard court this season. When you keep winning, maybe it's tough physically and mentally. But now I'm in good shape.'

Murray won his 14th match at Flushing Meadows against four defeats as he prevailed over Capdeville, 87th on the ATP.

The Scot's five 2009 titles have him tied with Rafael Nadal for the most on tour this year. Having been the first player to win 50 matches this season, he was also in joint first place with Novak Djokovic for most match wins coming into the US Open with 53.

Slimmed-down seventh seed Jo-Wilfried Tsonga cut short the wrist injury comeback of Jarkko Nieminen as he defeated the Finn 7-5, 6-3, 6-4.

The 2008 Australian open finalist will next face fellow Frenchman Julien Benneteau, who beat Serb Viktor Troicki 6-1, 3-6, 6-1, 6-0.

'It was a quick match,' said Tsonga, who broke once in each set to get past Nieminen as the Finn played only his third match after missing four months due to his wrist operation.