World No 1 Andy Murray got past Russia's Andrey Kuznetsov 6-4, 4-6, 6-2, 6-0 and Stan Wawrinka beat Jozef Kovalik 6-2, 7-6 (6), 6-3 in their respective first round matches at the French Open. Meanwhile, Alexander Zverev slumped to a 4-6, 6-3, 4-6, 2-6 defeat to Spain's Fernando Verdasco.
Murray, struggling for form, made a patchy start that saw the world No 73 Kuznetsov break him four times - twice while taking the second set. However, the Briton world No 1 found his rhythm to complete a gruelling four-set victory.
"It definitely got better as it went on," Murray said after the victory. "I started to move a bit better towards the end and was hitting the ball better when I was defending. That's something the last few weeks I haven't done so well and didn't start off the match doing particularly well.
"But once I was getting a little bit more on my ball when I was defending, there wasn't too many openings for him in the points."
Third seed Wawrinka had an easy outing in defeating Slovakian qualifier Kovalik. The Swiss saved two set points in the second-set tiebreaker before winning the game.
Argentine star Juan Martin del Potro, who made a return to the French Open after a five-year sabbatical, defeated compatriot Guido Pella 6-2, 6-1, 6-4. However, German ninth seed Zverev, who is touted as a potential French Open champion, bowed out.
In women's singles, Ukrainian fifth seed Elina Svitolina secured a 6-4, 6-3 win over Kazakhstan's Yaroslava Shvedova while Polish ninth seed Agnieszka Radwanska got the better of France's Fiona Ferro 6-1, 6-1.
In men's doubles, Britain's Jamie Murray and his Brazilian partner Bruno Soares eased past the Serbian pair of Janko Tipsarevic and Viktor Troicki 6-3, 7-6 (0) in a first round match.