Argentine Juan Martin del Potro survived an injury scare and sweltering 30-degree heat to book his place in the second round of the French Open with a 6-2 6-7 6-2 6-1 win against Spain's Albert Montanes.
The ninth-seeded Del Potro, a Roland Garros semi-finalist in 2009, received lenghty treatment on a sore left knee at the end of the second set before motoring through to prevail with a service winner on his first match point in a shade over three hours.
The 2009 US Open champion started brightly, sprinkling the court with forehand winners to open a 6-2 4-2 lead before seizing up as claycourt specialist Montanes fought back to take the second-set tie-break 7-5.
Del Potro, however, regrouped after the trainer strapped his left knee to set up a second-round meeting with home favourite Edouard Roger-Vasselin.
The 23-year-old, the only man outside of Novak Djokovic, Rafael Nadal and Federer to win a Grand Slam title in the last seven years admitted afterwards that the soaring temperatures were taking their toll.
"I was struggling a little, but I had some good treatment which allowed me to finish the match," said Del Potro.
"Roland Garros is a physically-demanding tournament. I have to keep that in mind as I am playing well at the moment."
He added: The pain started after (the event in) Madrid.
"I'm still working with the physio every day, trying to recover and to feel better for the matches.
"It is a problem when you can't find your balance as you're used to, but I'll use these few days of rest to get better.
"If I go on the court, it's because I feel good. I want to continue playing.''
Also making the last 64 on the opening day of the 2012 tournament was 2003 winner Juan Carlos Ferrero, who defeated French wildcard Jonathan Dasnieres de Veigy 6-1 6-4 6-3.
Ferrero, playing in his 12th Roland Garros, next meets Croatian 21st seed Marin Cilic who defeated Spain's Daniel Munoz 6-4 6-4 7-5.
Stanislas Wawrinka also progressed after surviving a scare against Italy's Flavio Cipolla.
The Swiss number two, seeded 18th, looked to be in control when he won the opening two sets against unheralded Italian Flavio Cipolla, but contrived to lose the next two and the match went into a decider.
Wawrinka roared into a 3-0 lead, though, and went on to complete a torturous 6-3 6-3 4-6 3-6 6-2 win.
Fernando Verdasco also progressed to the next round thanks to a comfortable straight sets victory against Belgian Steve Darcis.
The Spanish 14th seed came through 6-3 6-2 7-6 (7-4).