Novak Djokovic was forced to battle back in a dramatic deciding set to overcome the spirited challenge of Gilles Simon at the Monte-Carlo Masters.
The Serbian, who has recently recovered from a lingering right elbow injury, took the first set before the Frenchman took the next to send the match into a decider.
Monaco resident Djokovic, the 2013 and 2015 champion, was broken at 4-4 in the decider but then reeled off three straight games to snatch a 6-3 3-6 7-5 victory over the World No.32 Simon in two hours and 30 minutes.
He will play the winner of the match between Russia's Karen Khachanov or Pablo Carreno Busta from Spain in the third round.
"It was a very difficult match, with many changes of momentum," Djokovic said.
"It was very tiring for me, the first clay of the season.
"But this is the start of the Roland Garros build-up."
David Goffin made it safely through into the third round after beating Spain's Nicolas Almagro. The 10th seed sailed through 7-5 6-1 in 70 minutes.
Earlier, local favourite Jo-Wilfried Tsonga, back from a one-month lay-off, was knocked out by fellow Frenchman, qualifier Adrian Mannarino, 6-7(3) 6-2 6-3.
Meanwhile, Andy Murray is confident he is ready to return to action at the Monte-Carlo Masters following an elbow injury.
The World No.1 is set for a first competitive match since early March when he takes on Luxembourg's Gilles Muller in the second round of the clay court tournament today.
Murray last played in Indian Wells and missed Great Britain's Davis Cup defeat against France as he continued his recovery.
But the Scot believes he is now in good shape to resume the build-up towards the French Open, where he was runner-up in 2016, and defending his Wimbledon title this summer.
"I would not start the tournament unless I felt comfortable doing that (going full tilt)," Murray said.
"I have only been really serving at my normal pace the last couple of days as I was trying to build it up slowly to time it right for the beginning of the tournament… and the elbow has been feeling better every day, so I am positive about that."
Murray, who received a bye into the second round, added: "It is not going to be easy, the first tournament coming back after a while, but I am feeling good and hopefully I can do it."
Muller, 33, defeated Tommy Robredo 6-2 6-2 in their first-round contest.
Murray has won all his previous five matches against the World No.28.