Top-seeded Kei Nishikori has opened his bid for a fourth straight Memphis Open tennis title with a 6-2 7-5 victory over American Ryan Harrison.

Nishikori was cruising through the second set on Wednesday night, up a break at 5-3. Harrison held serve, then broke the Japanese player in the lengthy 10th game. The American saved four match points before Nishikori hit a backhand into the net, giving Harrison his break and tying the set at 5-5.

Nishikori, the world No.7, broke back in the next game and then served out the match to move to the third round and set up a showdown with Kazakhstan’s Mikhail Kukushkin, who upset fifth-seeded Denis Kudla 6-1 7-5.

“I think he (Harrison) started playing a little better that game,” Nishikori said about the 10th game. “I kind of had a double fault (up 40-30), something, easy mistakes. I should’ve closed out. But happy to finish the last two games.”

Throughout the evening match, Nishikori countered Harrison’s strong serve with a strategy of running the American from side-to-side along the baseline with an occasional drop shot to keep him off balance. Harrison has only won once in 25 matches against top-10 players.

Nishikori and Kukushkin faced each other in the round of 16 at Brisbane in January with Nishikori defeating Kukushkin 6-3 6-4 on a similar hardcourt as this week’s tournament.

“It was two sets, but it was a tough one,” Nishikori said. “He’s always (a) tough player. Especially with this slow condition, it’s going to be many long rallies. I’m going to have to stay tough.”

Kukushkin, ranked 93rd in the world, made a quick start in the opening set against Kudla, the American who entered the tournament at career-best ranking of 59th. The second set was more competitive, but Kudla was unable to overtake Kukushkin.

In other second-round matches, fourth-seeded Sam Querrey of the United States beat Henri Laaksonen of Switzerland 6-3 6-4, and Japan’s Yoshihito Nishioka accounted for Ukraine’s Illya Marchenko 6-1 6-3.