Belgian Steve Darcis claimed the scalp of Andy Roddick as he beat the American in the last 16 of the Winston-Salem Open in North Carolina.
Darcis had lost on the two previous occasions the pair had met, most recently at Eastbourne in June when he abandoned their match when trailing due to injury.
But on this occasion Darcis edged it, taking victory on two tie-breaks as he overcame Roddick 7-6 (8/6) 7-6 (7/3).
In the previous round, Roddick had beaten his fellow American James Blake by an almost identical scoreline.
Despite being given plenty of practice of tie-breaks, Roddick said: "I wanted to play better here."
Darcis, who had beaten his fellow Belgian Xavier Malisse and Uzbekistan's Denis Istomin in the first two rounds, was delighted to sink the former US Open champion, ahead of next week's start of the year's final grand slam at Flushing Meadows.
He said on atpworldtour.com: "I didn't expect this when I came here, I wasn't playing well. I've played two good first matches and now I have played well, serving well and trying to be aggressive when I could. Of course it is a good win before the US Open."
Czech second seed Tomas Berdych awaits Darcis in the quarter-finals, after a 6-3 6-2 victory over Finland's Jarkko Nieminen.
French top seed Jo-Wilfried Tsonga came through 7-6 (7/1) 6-4 against Ukrainian qualifier Sergiy Stakhovsky, while American John Isner fired 14 aces in his 6-4 6-3 triumph over Austrian Jurgen Melzer.
There were also last-16 wins for Sam Querrey, Alexandr Dolgopolov, Marcel Granollers and David Goffin.