Darkness halted Andy Murray's bad-tempered French Open survival battle with Radek Stepanek while Stan Wawrinka avoided becoming the first defending champion to lose in the first round on Monday.
Second seed Murray dropped the first two sets 6-3, 6-3 before taking the third 6-0.
He then edged ahead with a break in the fourth at 4-2 when play was halted in the gloom of Court Philippe Chatrier at 2123 (1923GMT).
At 37, Stepanek is bidding to be the oldest winner of a singles match in Paris since Jimmy Connors in 1991.
And he appeared to be cruising to a shock win over the three-time semi-finalist when he swept the first two sets.
But Murray's greater stamina and his eight-year age advantage resulted in a dramatic turnaround as he took the third in just 18 minutes. But he was ordered to keep playing and when the tie was halted it was Murray in the ascendancy ahead of a Tuesday resumption where he will attempt to avoid his first opening round exit in Paris since his 2006 debut.
Wawrinka needed five tough sets to get past Stepanek's equally combative and fiesty Czech compatriot, Lukas Rosol.
Third seed Wawrinka fired 56 winners but committed 46 unforced errors and needed to save eight break points to book a second round clash against Japan's Taro Daniel.
Wawrinka, 31, had defeated 59th-ranked Rosol in the semi-finals of the Geneva clay-court tournament just last Friday.
But Rosol went into the match on a chilly Court Philippe Chatrier with the pedigree of having famously stunned Rafael Nadal at Wimbledon in 2012.
That free-swinging masterclass almost paid dividends again Monday but once he had let slip two break points at 2-2 in the fourth set, his hopes slowly faded.
However, there was time for a notable first.
Qualifier Cagla Buyukakcay beat Aliaksandra Sasnovich of Belarus 5-7, 7-6 (7/2), 6-2 to become the first Turkish woman in the Open era to reach the second round of a Grand Slam.
Canadian eighth seed Milos Raonic, a 2014 quarter-finalist, defeated Serbia's Janko Tipsarevic 6-3, 6-2, 7-6 (7/5).
Tipsarevic was playing his first Roland Garros since 2013 after being treated for a benign tumour on his left foot.