Bucharest, Romania (SportsNetwork.com) - Top seed and three-time tournament champion Gilles Simon suffered a quarterfinal setback, while his fellow Frenchman Gael Monfils avoided an upset Friday at the BRD Nastase Tiriac Trophy tennis event.

Spaniard Daniel Gimeno-Traver tripped up France's Simon in come-from- behind 6-7 (5-7), 6-4, 6-2 fashion on the red clay at Arenele BNR.

"It was a complicated and tough match," said Gimeno-Traver. "I think that the key was me being aggressive and taking initiative. It's a good period for me and I'm looking forward to tomorrow's semifinal."

The second-seeded Monfils moved on by dismissing eighth-seeded Italian Simone Bolelli 6-3, 7-6 (7-4).

However, more upsets came when seventh-seeded Czech Jiri Vesely took out third-seeded 6-foot-10 Croat Ivo Karlovic 6-4, 6-4 and, in a rematch of the 2013 final, fifth-seeded Guillermo Garcia-Lopez of Spain avenged a loss from two years ago by dousing fourth-seeded Czech slugger Lukas Rosol 6-4, 7-6 (9-7).

No less than three top-four seeds bowed out on Friday.

Rosol was last year's runner-up to Bulgarian star Grigor Dimitrov after capturing the Bucharest title in '13 by beating Garcia-Lopez in that finale.

Saturday's semis will pit Monfils against Garcia-Lopez and Vesely versus Gimeno-Traver.

The 2015 Bucharest champion will earn $86,400.