PHOTOS: French Open (Day V)

Czech fourth seed Petra Kvitova strolled into the French Open third round with a comprehensive 6-1, 6-3 win over Pole Urszula Radwanska on Thursday.

Kvitova, who had only dropped three games in her opening round, was never threatened by the world number 79, hitting 30 winners in a one-sided match on Court Suzanne Lenglen.

The Wimbledon champion ended Radwanska's misery after 70 minutes on her second match point when the Pole sent a backhand long.

Kvitova, heading towards a possible quarter-final clash with defending champion Li Na of China, will next face Frenchwoman Claire Feuerstein or Russian Nina Bratchikova.

Holder Rafael Nadal continued his march towards a record-breaking seventh French Open title with a 6-2, 6-2, 6-0 demolition of Uzbekistan's Denis Istomin in the second round on Thursday.

The second-seeded Spaniard tormented his 43rd-ranked opponent with his mix of power and accuracy to seal victory in less than two hours on Court Suzanne Lenglen.

Nadal, bidding to surpass the mark of six Roland Garros title he jointly holds with Swede Bjorn Borg, prevailed on his first match point with his 19th forehand winner.

Nadal, who has only dropped nine games in his first two matches and lost only one match since his debut on the Paris clay in 2005, will next face German 32nd seed Florian Mayer or Argentine Eduardo Schwank.

World number four Andy Murray battled through back pain to win his second-round match at the French Open against Finn Jarkko Nieminen on Thursday.

The Briton, who at times in the first set looked like he would not be able to continue, won 1-6, 6-4, 6-1, 6-2, and will face unseeded Colombian Santiago Giraldo in the third round.

Murray, a semi-finalist in Paris last year, summoned the trainer three times during the opening set and lay on a towel, grimacing in pain, as his back was massaged.

Murray, who had to withdraw from the Madrid Masters this month with a back problem, opted to stand during changeovers but began to move more easily as the match progressed.

The 48th-ranked Nieminen, though, was unable to take advantage of Murray's troubles and hit more unforced errors than the Scot in the later sets.

When he put a backhand out to give Murray breakpoint in the seventh game of the final set, Nieminen threw his racket to the clay and stamped on it. A double fault followed, and Murray went 5-2 up.

Jo-Wilfried Tsonga called playtime over on Thursday when he booked his place in the French Open third round with a 6-2, 4-6, 6-2, 6-1 victory over German Cedrik-Marcel Stebe.

The fifth-seeded Tsonga was level at one set all and 1-1 in the third when play resumed after being interrupted by rain on Wednesday and he was just too sharp for the world number 90.

"Yesterday the wet conditions were not favouring me. I was not able to play my usual (attacking) game. I could not serve an ace, could not fire winners from the baseline," Tsonga told a news conference.

"In that case, we are in a game of cat and mouse and I'm not too good at that. I could not focus, I was starting to lose it a bit."

Tsonga, the last Frenchman to reach a grand slam final, at the 2008 Australian Open, started with a break and never looked back.

He needed just under an hour on court to finish off Stebe and set up a meeting with Serbian 28th seed Viktor Troicki or Italian Fabio Fognini.