Japan's Kei Nishikori edged Andreas Seppi of Italy 6-0, 2-6, 6-3 Thursday to reach the quarterfinals of the Monte Carlo Masters, his first clay court tournament of the season.

Up 3-2 in the third set, Nishikori, who returned to the ATP Tour in February after a season-ending wrist injury last summer, turned the tide in the sixth game when he broke Seppi's serve and pulled away to join the final eight.

"There were moments I felt like I was playing ideal tennis," said Nishikori, who closed out the first set in 25 minutes.

"I'm getting better with every game. I'm finding my rhythm. It's tough, but I'm managing alright," he said.

The 28-year-old survived a scare in the second set when the 62nd-ranked Seppi, cheered on by the pro-Italian crowd, capitalized on Nishikori's first-serve errors to win five straight games.

Nishikori opened the third set by holding serve, hitting a crosscourt backhand winner to close the game.

"I was in attack mode (in the third set). It was good that I was able to play aggressively in key situations," Nishikori said.

"I was able to play offensive tennis in the third set."

Former world No. 4 Nishikori, now ranked 36th, will face world No. 3 and second-seeded Marin Cilic of Croatia on Friday in their 14th head-to-head. Nishikori is 7-6 against the big-serving Cilic, who was beaten by Roger Federer in the Australian Open final in January.

Cilic reached the quarterfinals in Monaco after being handed a walkover against injured Canadian 14-seed Milos Raonic.

Meanwhile, Novak Djokovic was downed by fifth seed Dominic Thiem in their third-round match, while top seed Rafael Nadal safely advanced to set up a meeting with the Austrian.