Memphis - Top seed Kei Nishikori kept his bid for a third straight ATP Memphis title alive on Friday with a 4-6, 6-3, 6-4 quarter-final win over Austin Krajicek.
The 25-year-old Japanese star, ranked fifth in the world, needed two hours and 10 minutes to subdue the American qualifier, ranked 156th.
Nishikori seized control in the third set with an early break for a 2-0 lead.
Krajicek broke to level the set at 4-4, but Nishikori immediately broke back to avert the danger and served out the match.
"Obviously I didn't play my best tennis, but I won today, that's meaningful," said Nishikori, last year's US Open runner-up and a quarter-finalist at this year's Australian open.
"I think it's a very good win today because he was playing good tennis... He was hitting a lot of aces that I wasn't really expecting."
Nishikori, who saved eight of the 10 break points he faced, next faces American Sam Querrey, who toppled third-seeded compatriot John Isner 7-6 (7/3), 7-6 (7/2).
Krajicek said Nishikori played better on the important points.
"Kei, obviously he's one of the best players in the sport, so he comes up with it when it matters," said the 24-year-old American, who saved two match points in a first-round win over Mikhail Kukushkin then downed fifth-seeded Ivo Karlovic in the second.
"I gave myself an opportunity and thought I played well. It was a really fun match and the atmosphere was great - I enjoyed myself."
Second-seeded South African Kevin Anderson also advanced, downing American Steve Johnson 6-4, 6-4.
Anderson fired 16 aces and saved all three break points he faced in the 65-minute contest. He'll take on American Donald Young, who defeated Australian Bernard Tomic 7-6 (10/8), 4-6, 7-5 to reach the semi-finals.
"I got a little nervous there at the end, but I was happy to come through," said Young, who reached the fourth ATP Tour semi-final of his career.
"Anytime you make the weekend, you're playing well. I made the weekend. It hasn't happened too often in my career, so when it happens I'm very excited."
Results on Friday from the fifth day of the ATP Memphis Open (x denotes seed):
Kei Nishikori (JPN x1) bt Austin Krajicek (USA) 4-6, 6-3, 6-4
Sam Querrey (USA) bt John Isner (USA x3) 7-6 (7/3), 7-6 (7/2)
Donald Young (USA) bt Bernard Tomic (AUS) 7-6 (10/8), 4-6, 7-5
Kevin Anderson (RSA x2) bt Steve Johnson (USA x6) 6-4, 6-4