Paris: Defending champion Stan Wawrinka dazzled the moment he walked on to a gloomy Philippe Chatrier Court wearing a fluorescent yellow shirt but his play only occasionally matched his attire as he flirted with a humbling first-round exit on Monday.
The 31-year-old third seed was left in the shade by straight-hitting Czech Lukas Rosol for much of their first-round clash but finally came to life to win 4-6, 6-1, 3-6, 6-3, 6-4.
It was touch and go for a while, though, as Rosol, who famously beat Rafael Nadal in the Wimbledon second round in 2012, threatened another huge upset on a damp and dreary day that began two hours late because of heavy rain.
"A really tough match, the conditions were slow and heavy," Wawrinka, relieved to avoid becoming the only defending French Open men's champion in the professional era to lose in the first round, told reporters.
"He kept me under pressure permanently. I kept running after the score. You can't really relax."
It was that kind of day, one for grit over style and Spain's fourth seed Garbine Muguruza, a Wimbledon finalist last year, showed plenty as she too avoided an early exit.
Wearing a long-sleeved top like most of the women players, the flat-hitting Spaniard took a while to find her game but eventually ground past 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.
Russian Svetlana Kuznetsova, champion 10 years ago, also toiled away to beat Yaroslava Shvedova as the seeds, apart from a few exceptions such as seventh seed Roberta Vinci, flourished.
Some advanced to the second round with a flourish, namely second seed Agnieszka Radwanska of Poland and Romania's Simona Halep, the sixth seed.
Halep, beaten by the currently suspended Maria Sharapova in the 2014 final, beat Japan's Nao Hibino 6-2, 6-0 while Radwanska, looking to go beyond the quarter-final for the first time, dispatched Serbian Bojana Jovanovski 6-0, 6-2.
Vinci was crushed 6-1, 6-3 by Ukraine's Kateryna Bondarenko.
It was a shock-free day in the men's draw with a batch of seeds moving through, led by number five Kei Nishikori.
The Japanese, a semi-finalist in Madrid and Rome in the build-up to Roland Garros, followed Wawrinka on to Chatrier with his job already half done against Simone Bolelli.
He carried on where he left off before rain halted play on Sunday, easing to a 6-1, 7-5, 6-3 victory.
He was joined in the second round by eighth seed Milos Raonic and 16th seed Gilles Simon who delighted the hardy home fans by beating Brazil's Rogerio Dutra Silva 7-6 (5), 6-4, 6-2.
Viktor Troicki ended the hopes of former top-tenner Grigor Dimitrov.