Benoit Paire fought off four match points at the Dubai Championships on Tuesday, overhauling former US Open winner Marin Cilic 2-6, 7-5, 7-6 (7/1) to reach the second round, while fourth seed Fabio Fognini was dumped out by Brit Dan Evans.
Eighth seed Paire appeared all but finished as Croatian Cilic, leading 5-3 in the second set after taking the first, served for a straight sets win.
But Frenchman Paire broke as he clung on and then won the set in the opening match of the day played in desert conditions in which temperatures reached 29 degrees Celsius (82.4 degrees fahrenheit).
"It was not easy today. I was not confident before the match. Normally when it's one set, 5-3, I normally tank," Paire said.
"This time I tried until the end. It was working good. I'm really happy about the win.
"I was not feeling really good on court. I was a little bit sick (the last) two, three days. But I was happy to win today and to fight until the end."
Paire, who lost to Cilic in the second round of last month's Australian Open, recovered from a break down in the final set and saved match points in the 12th game to take it into a tiebreaker.
He then charged to five match points before Cilic double-faulted for a 10th time to hand the win to Paire, who will play countryman Richard Gasquet next.
Italian Fognini, making his Dubai debut, was knocked out after nearly two and three-quarter hours on Evans' sixth match point.
The Briton claimed a 3-6, 6-4, 7-5 victory after an eight-minute final game which ended as a return on the Fognini baseline was called good by the Hawk-Eye system.
"It's difficult to play Fabio, he's such a class player," Evans said of the world number 11.
"I'm just happy to come through really. It felt like he was on top forever really, I was just hanging in."
Later second seed Stefanos Tsitsipas, who lifted the Marseille title at the weekend, faces Spain's Pablo Carreno Busta.
Other Tuesday winners included qualifiers Dennis Novak of Austria and Japan's Yasutaka Uchiyama.
Filip Krajinovic advanced past Joao Sousa with a 4-6, 6-3, 6-3 comeback to next play sixth seed Andrey Rublev.
Japan's Yoshihito Nishioka, who lost the Delray Beach final in Florida on Sunday, rushed to the Gulf only to go down 7-5, 6-2 to France's Pierre-Hugues Herbert in the first round.
France's Benoit Paire is yet to reach further than the fourth round of a Grand Slam in the singles draw