Holder Stan Wawrinka avoided a repeat of his French Open first-round scare although the Swiss was still made to work hard for a straight-sets win over Japan's Taro Daniel today.
The third seed won 7-6(7) 6-3 6-4 on a sunny Court Suzanne Lenglen, although it was by no means straightforward against a skilful opponent ranked 93rd in the world.
Wawrinka, who needed five sets to scrape past Lukas Rosol in the opening round, found himself in trouble in the first set when he had two save two set points.
He dominated the second set but was a break down in the third before finishing with a flourish to secure a third round clash against French 30th seed Jeremy Chardy.
"I'm very satisfied after a tough first match," the 31-year-old Wawrinka, again sporting a dazzling fluorescent yellow shirt, said in an on-court interview.
"Happy to be through in straight sets. I managed to be tougher with myself in the key moments. All in all I stayed focused on what I had to do."
Japan's Kei Nishikori maintained his impressive clay-court form to outclass Russian Andrey Kuznetsov 6-3 6-3 6-3 in their second round match.
The fifth seed, a quarter-finalist at Roland Garros last year, had too much in his armoury for 40th-ranked Kuznetsov on a sun-bathed Court One, although he made a slow start.
He dropped serve in the third game of the match when he drove a forehand long, but broke back quickly with a rasping backhand to finish off a fierce 24-stroke rally.
Another break of serve secured the set.
Kuznetsov served a double-fault to gift Nishikori a break in the fifth game of the second set and the Japanese player moved 5-2 ahead with some punishing ground strokes.
A lapse in concentration allowed Kuznetsov to break back but that was only a minor inconvenience as Nihsikori broke the Russian's serve in the next game with sweetly struck forehand winner.
Nishikori was playing well inside his comfort zone as he eased through the third set and sealed the win with another sublime backhand pass.
Croatian Ivo Karlovic became the oldest man to reach the third round of a grand slam for 25 years when the 37-year-old came through a marathon five-setter against Australian Jordan Thompson.
Karlovic, seeded 27, banged down 41 aces in a 6-7(2) 6-3 7-6(3) 6-7(4) 12-10 victory against the 22-year-old wildcard.
He broke serve at 10-10 and sealed a memorable victory with a volley after four hours and 31 minutes, the longest match of this year's tournament so far.
Jimmy Connors reached the third round at the French and U.S. Opens in 1991, aged 38.
Karlovic will face either second seed Andy Murray or France's Mathias Bourgue for a place in the last 16 at Roland Garros for the first time.
