Defending champion Stan Wawrinka breathed a huge sigh of relief and Andy Murray faced a sleepless night after both got bogged down by belligerent Czechs at a sodden French Open.
A day that began two hours late after torrential rain ended with world number two Murray hanging on against 37-year-old Czech qualifier Radek Stepanek having lost the opening two sets in the Philippe Chatrier Court gloom.
When play was finally suspended Murray had repaired some of the damage but still trailed 3-6 3-6 6-0 4-2.
Third seed Wawrinka did book his place in the second round, although his path to victory against straight-hitting Lukas Rosol was equally tortuous.
The Swiss, decked out in an eye-straining fluorescent yellow shirt, was left in the shade by the world number 59 and twice trailed by a set before his opponent tired and he scratched out a 4-6 6-1 3-6 6-3 6-4 victory.
Wawrinka puffed out his cheeks after tucking away a volley on his third match point, happy to have avoided becoming the first defending men's champion to lose his opening match since Australian Lew Hoad in 1957.
It was touch and go, however, as Rosol, who famously knocked out Rafael Nadal in the Wimbledon second round in 2012, threatened another huge upset with his murderous groundstrokes.
"A really tough match, the conditions were slow and heavy," Wawrinka, who only arrived on Saturday hours after winning the Geneva title, told reporters.
"He kept me under pressure permanently. I kept running after the score. You can't really relax."
Murray, second favourite to de-throne Wawrinka after world number one Novak Djokovic, had to wait until 7pm local time to take on tricky Stepanek, the oldest man in the draw.
He might have hoped to polish off the world number 128 in time for dinner, but Stepanek had other ideas.
With Murray off-key, Stepanek used his full range of slices, pinpoint forehands and bamboozling drop shots to torment the twice grand slam champion.
A fraught Murray dropped serve with a double-fault and conceded the opening set with a misfired forehand.
The second set went the same way as Stepanek delighted a sparse crowd with his repertoire.
Murray, scolding himself into action, waltzed the third set and was a break up in the fourth. Yet Stepanek will return on Tuesday believing he can become the oldest man to win a round at Roland Garros since Jimmy Connors (aged 38) in 1991.
Three fancied players did succumb on a cheerless day.
Former U.S. Open champion Marin Cilic, seeded 10, went down to Argentine qualifier Marco Trungelliti 7-6(4) 3-6 6-4 6-2.
It was a poor day for Italians in the women's draw where seventh seed Roberta Vinci was crushed 6-1 6-3 by Ukraine's Kateryna Bondarenko and 16th seed Sara Errani, runner-up in 2012, lost to Bulgaria's Tsvetana Pironkova 6-3 6-2.
Fourth seed Garbine Muguruza, a Wimbledon finalist last year, showed plenty of grit as she avoided an early exit.
Wearing a long-sleeved top like most of the women players, the flat-hitting Spaniard took a while to warm up before eventually overpowering Anna Karoline Schmiedlova 3-6 6-3 6-3.
"It was so cold. Even though I was running and playing, I felt like cold. I thought it was going to rain. I was looking to the sky," Muguruza told reporters.