Jarkko Nieminen upset Nikolay Davydenko 6-3 7-6 (10/8) to reach the quarter-finals of the Open Sud de France in Montpellier.
The Finn managed three breaks of serve as he recorded his first win over the fifth seed in nearly 10 years, his last success over the Russian having come on clay at the Rome Masters.
Nieminen was forced into a tie-break as Davydenko survived match point in the second set but held his nerve to reach the last eight in the tournament for the second successive year.
The 31-year-old will face either Sergiy Stakhovsky or Tatsuma Ito in the last eight after the former recovered from a set down to beat France's Edouard Roger-Vasselin 3-6 7-6 (7/5) 7-5.
In other first-round matches, sixth-seeded Julien Benneteau of France led 6-3 4-2 against Adrian Ungur when the Romanian was forced to retire with a thigh injury.
Arnau Brugues-Davi of Spain needed three sets to see off Kazakh Mikhail Kukushkin by a 6-7 (5/7) 6-3 7-6 (7/3) scoreline and set up a second-round clash with fourth seed Gilles Simon.
Benoit Paire awaits the winner of that match, the Frenchman having come through a tough three-set encounter himself against Belgium's Steve Darcis, eventually triumphing 4-6 7-6 (13/11) 6-4.
Meanwhile, Michael Llodra is next up for second seed Janko Tipsarevic after dispatching fellow Frenchman and lucky loser Kenny De Schepper 6-3 6-3.