Roddick, the fifth seed and the last American to win the title here in 2003, coasted through 6-1, 6-4, 6-4 against Frenchman Marc Giquel in a match that finished after midnight on Thursday.
The giant 21-year-old Querrey, who this summer has taken over as the US number two, defeated compatriot Kevin Kim 7-5, 6-7 (6), 6-4, 6-4 and is just two wins from a possible quarterfinal match against top seed and title-holder Roger Federer.
Joining Roddick and Querrey in the third round of the top half of the draw were former US No 1 James Blake, who edged Olivier Rochus of Belgium 6-4, 3-6, 7-6 (6), 6-3, and another outsized US player in John Isner, who blasted past Turkey’s Marsel Ilhan 6-3, 6-4, 7-6 (1).
Earlier, compatriot Jesse Witten, a 26-year-old qualifier playing in just his second Grand Slam event, defeated Maximo Gonzalez of Argentina 6-7 (3), 6-4, 7-5, 6-2. Next up for him will be fourth-seeded Serb Novak Djokovic, who had little trouble in seeing off Australian qualifier Carsten Ball 6-3, 6-4, 6-4.
Another American failure in the men’s singles this year would make it six years in a row without a title, the worst winless run for home players since the Open era began in 1968.
Early play on Thursday saw 10th seed Fernando Verdasco of Spain and 20th seed Tommy Haas of Germany set up an intriguing third-round clash.
Verdasco, a semifinalist in the Australian Open at the start of the year, brushed aside Florent Serra of France 6-3, 6-0, 6-3, while Haas was too good for American Robert Kendrick, winning 6-4, 6-4, 7-6 (3).
Also through to the third round was Russian eighth seed Nikolay Davydenko, who defeated Jan Hernych of the Czech Republic 6-4, 6-1, 6-2. Davydenko was a semifinalist here in 2006 and 2007.
Jankovic, Dementieva fall
Fourth seed Elena Dementieva and fifth seed Jelena Jankovic were upset victims on Thursday while top-ranked Dinara Safina struggled but is now the only seed still in her quarter of the draw.
Russian stars Maria Sharapova and Svetlana Kuznetsova avoided the trend of shockers and breezed into the third round, but could feel the stress as Flushing Meadows favourites began to fall at Arthur Ashe Stadium. “You do sense it,” Sharapova said. “I saw some of the tough matches. You dont want to be that person.”
US teen Melanie Oudin shrugged off a sore left leg to stun 2004 US Open runner-up Dementieva 5-7, 6-4, 6-3, and leave the Russian still searching for her first Grand Slam crown.
It was the earliest US Open exit by the Russian since 2002, sent off by a 17-year-old American with “believe” written on her pink and yellow shoes. Yaroslava Shvedova, a 20-year-old Kazak ranked 55th in the world, outlasted former world number one Jankovic 6-3, 6-7 (4), 7-6 (6).
Top seed Safina, seeking her first Slam title, rallied to beat 67th-ranked German Kristina Barrois 6-7 (5), 6-2, 6-3. The Russian made 38 unforced errors and double faulted 15 times but endured a roller-coaster day to advance.
French Open champion Kuznetsova, the top remaining seed in her quarter of the draw, routed Latvia’s Anastasija Sevastova 6-4, 6-2. The sixth seed whose other Slam crown came at the 2004 US Open never faced a break point.
Sharapova, a former world number one back after right shoulder surgery, beat US teen Christina McHale 6-2, 6-1, and faces Oudin next. Safina battled through to a third-round meeting with 72nd-ranked Czech Petra Kvitova, who ousted Italy’s 58th-ranked Tathiana Garbin 6-1, 6-3. Six of eight higher-ranked players lost in Safina’s section, the last of them 23rd-seeded Sabine Lisicki.
Aussie qualifier Anastasia Rodionova ousted Lisicki 6-3, 3-6, 7-5 but the German twisted her left ankle on the final swing of the match and crumpled to the court screaming in pain. She was wheeled off still wiping her eyes.