Andy Murray and Juan Del Potro fuelled ambitions as dangerous title contenders on 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. "I played great. I'm happy to go through this far."
Tsonga confessed that he has dropped a few kilograms in recent months as he works on fitness, which showed as he displayed his powerful game against Nieminen in one and three-quarter hours.
Croatian 16th seed Marin Cilic staged a career-fist comeback from two sets to love down, overhauling US player Jesse Levine 4-6, 2-6, 6-0, 6-3, 6-0.
2003 New York finalist Juan Carlos Ferrero performed a similar feat as he came back to oust German Philipp Petzschner 1-6, 3-6, 6-4, 6-2, 6-4.
Second-seeded women's holder Serena Williams had to win a lengthy 11th game of the second set lasting seven deuces to overcome Maria Jose Martinez Sanchez 6-3, 7-5.
The pair have a history from the French Open, when Williams accused the Spaniard of cheating during their third-round match. But no boilovers occurred in New York.
"You can never underestimate anyone. Some people, some days they have great days," said Williams. "I was just happy to keep getting through my match.
"I just go and look at every opponent as the best player in the world. I just kept fighting, and every time I had a break point I felt like I had a chance to win one of them."
Russian Vera Zvonareva beat compatriot Elena Vesnina 6-2, 6-4 while veteran Italian Francesca Schiavone upset eighth seed Victoria Azarenka 4-6, 6-2, 6-2.
Tenth seed Flavia Pennetta of Italy crushed Canada's Aleksandra Wozniak 6-1, 6-1, while Daniela Hantuchova ended the upset run of Vania King 6-2, 6-2 after the Us player had beaten 15th seed Samantha Stosur in the previous round.