Kei Nishikori said Wednesday he was stunned to learn his former junior doubles partner Junn Mitsuhashi has been banned from tennis for life for attempted match-fixing and betting on the sport.

"I was shocked," Nishikori said, after winning his first match in two sets at the Italian Open against David Ferrer. "It's just surprising."

World No. 9 Nishikori partnered with Mitsuhashi at the 2005 Junior Davis Cup. On Tuesday, the 27-year-old Mitsuhashi was kicked out of tennis and fined $50,000 by the Tennis Integrity Unit, which punished a Japanese for the first time.

Nishikori considered Mitsuhashi, a former national junior high school champion who climbed no further than No. 295 in the world rankings, a former "friend" and was saddened to hear of his involvement on one of the darkest days in Japanese tennis.

"He used to be a friend," Nishikori said. "He's not a bad guy, really passionate. But he was pure and naive so I think he's the type who could be conned into doing something.

"He won't ever be able to play tennis again, but I hope he gets his life back together. I'd like that."