Ninth seed Gilles Simon booked his place in the third round of the Cincinnati Masters on Tuesday after a 7-6, 6-7, 6-1 win over Russian Igor Andreev.
After two tough sets, the Frenchman ran away with the decider to secure a meeting with either eighth seed Nikolay Davydenko or another Russian Igor Kunitsyn, who upset American James Blake 7-6, 6-7, 6-4.
Croatian 14th seed Marin Cilic was beaten 7-6, 6-2 by Spaniard David Ferrer in the day's other second-round encounter, while three other seeds went out in the first round.
Simon needed two hours 20 minutes to finally get the better of Andreev, who snatched the second-set tiebreak 10-8 to force a decider.
But in the end the Frenchman's superior fitness proved the key as he made it four wins out of four against the Russian to reach the last 16.
Simon has been struggling with a knee injury recently but said he was happy with the way he was hitting the ball.
"I'm actually playing good," he said. "I practised a lot but I have some frustration on the court because I just can't do what I want, I can't run as usual.
"It's not easy for me, because I like to fight. I like to feel that it's going to be hard for my opponent to win every point. That's not the way I'm playing."
Former world number one Lleyton Hewitt saved two match points on his way to beating 12th seed Robin Soderling 3-6, 7-6, 6-4.
The Australian, who has climbed back up the rankings to number 42 having slipped outside the top 100 earlier this year, was overpowered in the first set by Soderling, the runner-up at the French Open in June.
The Swede held match points at 6-5 and 8-7 in the second-set tiebreak but Hewitt held firm and after breaking in the first game of the deciding set, he held on for victory after two hours nine minutes.
"I felt it was a very high standard match," said Hewitt, who now plays Germany's Benjamin Becker. "Both of us hit the ball extremely well, we both hit it extremely clean.
"He's the kind of guy who's going to hit a lot of winners out there. You have got to make him play that one extra shot a lot of times."
Tenth seed Fernando Gonzalez retired after losing the first set 6-4 to Czech Tomas Berdych, while 11th seed Fernando Verdasco was beaten 7-6, 7-6 by fellow Spaniard Guillermo Garcia-Lopez, who now plays Russian Mikhail Youzhny, a 7-5, 6-2 winner over Romania's Victor Hanescu.
Italian Andreas Seppi secured a second-round meeting with world number three Rafa Nadal with a 3-6, 6-4, 6-1 victory over Czech Jan Hernych, while American wildcard John Isner edged out Tommy Haas 7-6, 5-7, 7-6 in the late match.
