Rome - Gilles Simon of France took advantage of a few key double-faults by Jack Sock and rallied for a 4-6, 7-6 (2), 6-3 win on Monday in the opening round of the Italian Open.
Sock was up a break in the second set until his usual commanding serve deserted him.
The 12th-seeded Simon quickly levelled the set and then jumped out to a 4-0 lead in the tiebreaker with the help of two double-faults by Sock.
Simon, who has won 12 ATP titles in his career, broke late in the third and closed it out at love in the final game.
Sock, a 22-year-old American ranked a career-high 33rd this week, appeared to lose energy as the match wore on and couldn't deal with Simon's consistency - committing twice as many unforced errors as the Frenchman (48-24).
With the temperature at the Foro Italico soaring above 25 degrees Celsius (nearly 80 Fahrenheit), fitness was key on the red clay courts.
Tenth-seeded Grigor Dimitrov also played cleanly in a 6-3, 7-6 (4) win over Jerzy Janowicz of Poland.
Dimitrov had only 11 unforced errors to Janowicz's 31.
A semi-finalist last year, Dimitrov improved to 9-3 on clay this year.
Also, Philipp Kohlschreiber of Germany beat Donald Young of the United States 6-4, 6-1.
In women's play, 15th-seeded Madison Keys defeated Madison Brengle 6-2, 6-4.
A semi-finalist at the Australian Open, Keys served seven aces to Brengle's one.
Also, Swiss player Timea Bacsinszky upset 11th-seeded Karolina Pliskova 6-4, 6-0 and improved to 26-5 this year; Anastasia Pavlyuchenkova of Russia beat Sam Stosur of Australia 6-4, 7-5; and Zarina Diyas of Kazakhstan eliminated Tsvetana Pironkova of Bulgaria 7-5, 6-1.
The Italian Open is the last big warm-up tournament for the French Open, which starts May 24.
Results from the second day of the ATP and WTA Italian Open on Monday (x denotes seeded player):
Anastasia Pavlyuchenkova (RUS) bt Samantha Stosur (AUS) 6-4, 7-5
Timea Bacsinszky (SUI) bt Karolina Pliskova (CZE/N.11) 6-4, 6-0
Madison Keys (USA x15) bt Madison Brengle (USA) 6-2, 6-4
Zarina Diyas (KAZ) bt Tsvetana Pironkova (BUL) 7-5, 6-1
Karin Knapp (ITA) bt Francesca Schiavone (ITA) 6-4, 6-1
Alison Riske (USA) bt Varvara Lepchenko (USA) 6-4, 6-3
Sara Errani (ITA) bt Daniela Hantuchova (SVK) 6-4, 7-6 (7/4)
Sabine Lisicki (GER) bt Sloane Stephens (USA) 6-4, 6-1
Gilles Simon (FRA x12) bt Jack Sock (USA) 4-6, 7-6 (7/2), 6-3
Grigor Dimitrov (BUL x10) bt Jerzy Janowicz (POL) 6-3, 7-6 (7/4)
Philipp Kohlschreiber (GER) bt Donald Young (USA) 6-4, 6-1
John Isner (USA/N.16) bat Joao Sousa (POR) 7-5, 6-3