Milos Raonic beat Julien Benneteau 6-1, 6-4 and Roberto Bautista Agut upset Gilles Simon 6-3, 7-6 (6) in the first round of the Monte Carlo Masters on Monday.
Raonic served 15 aces and broke his French opponent three times to set up a match against Jarkko Nieminen, who thrashed Viktor Troicki 6-1, 6-2.
Bautista Agut was pushed a little harder, closing it out on his fifth match point when the 11th-seeded Frenchman hit a forehand into the net.
The Spaniard will play either Florian Mayer or Benjamin Balleret.
"I didn't produce anything during that first set. In fact, I was tired. Long rallies were killing me,'' Simon said.
"In every game I was giving him a couple of free points, which hurts a lot on clay because from his side there were not many free points.''
It was Simon's fourth straight defeat after losing to Tommy Haas in the Sony Open quarterfinals and both singles matches in France's Davis Cup quarterfinal loss to Argentina.
Fabio Fognini came from behind to down 15th-seeded Andreas Seppi 3-6, 6-4, 6-4 in an all-Italian match after converting seven of 10 breakpoint chances.
He faces either Radek Stepanek or qualifier Albert Ramos.
In other first-round matches, there were wins for Nikolay Davydenko, qualifier Pablo Andujar and French pair Benoit Paire and Edouard Roger-Vasselin.
Davydenko beat qualifier Daniel Brands 6-3, 6-4; Andujar scraped past Jeremy Chardy 6-7 (4), 7-5, 6-2; Paire won 6-4, 6-4 against Ivan Dodig, and Roger-Vasselin topped Robin Haase 6-3, 6-2.
Later, ninth-seeded Marin Cilic will play Horacio Zeballos.
Top-seeded Novak Djokovic will decide on Tuesday whether he's recovered from his ankle problem to play either Mikhail Youzhny or Daniel Gimeno-Traver on Wednesday, when No. 2 Andy Murray takes on Roger-Vasselin.