Top seed Nikolay Davydenko only had himself to blame when he was dumped out of the New Haven Open on Wednesday, his poor preparation leading to a 6-1, 7-6 loss to Argentine Juan Ignacio Chela in the second round.
In the women's event, second seed Amelie Mauresmo romped past Russian Elena Likhovtseva 6-1, 6-3 to reach the quarter-finals, while Daniela Hantuchova battled past sixth seed Patty Schnyder to set up a clash with top seed Lindsay Davenport.
Russian Davydenko was completely out of sorts in the first set and despite improving in the second, was no match for Chela, who will next meet Frenchman Fabrice Santoro in the final warm-up event before next week's U.S. Open.
Santoro upset his 13th-seeded compatriot Paul Henri Mathieu 6-4, 7-6.
A rueful Davydenko, who reached the semi-finals at the French Open, said: "Today was my mistake.
"I came here from Cincinnati and here the balls and the courts are different, so I changed the tension on my rackets to give me more control.
"In practice, it was good but today the weather was maybe different and I couldn't do anything.
"I had made four of my five rackets tighter, for more control, but when it was 6-1, 3-0, I changed to my old one and started to play well. Then I broke my string at 6-5 and had to use the new ones again.
"If I'd won the second set, I'd probably have lost 6-1 like in the first.
"It's better that it happened here than at the U.S. Open, and now I can rest a bit and prepare more."
FEW PROBLEMS
Crowd favourite James Blake experienced few problems as he marched into the third round with a 6-1 6-3 victory over Italian 10th seed Filippo Volandri.
American Blake, who reached the final in Washington earlier this season, will now meet sixth seed Tommy Haas of Germany, who rallied to beat Christophe Rochus 6-2, 4-6, 6-0.
Second seed Fernando Gonzalez of Chile advanced with a 6-2, 3-6, 6-4 win over American Justin Gimelstob while third-seeded David Ferrer of Spain, Chilean seventh seed Nicolas Massu and number 12 Vince Spadea of the U.S. all reached round three.
However, eighth seed Olivier Rochus of Belgium, number 10 Juergen Melzer of Austria and 16th seed Gael Monfils of France all crashed out.
In the women's event, Mauresmo looked sluggish early on but broke Likhovtseva's serve in the third game to take control.
Likhovtseva, a semi-finalist at the French Open, offered little resistance thereafter and the Frenchwoman reeled off 10 games in a row to lead by a set and 4-0.
The Russian improved to break the Mauresmo serve and pull it back to 5-3, but the former world number one broke again in the next game to seal her place in the last eight.
There she will meet German Anna-Lena Groenefeld, who beat American Meghann Shaughnessy 6-3, 7-5.
Hantuchova, who has climbed back up to number 21 in the world this year, rallied from a set behind to beat Schnyder 5-7, 6-2, 6-4.
Russian Anna Chakvetadze ousted her compatriot Maria Kirilenko 6-3, 6-3, while Jie Zheng of China, who made it into the main draw when Nadia Petrova withdrew through injury, beat Jamea Jackson of the U.S.
