MEMPHIS, Tenn. -- Defending champion Kei Nishikori of Japan rallied to beat Russian Alex Bogomolov Jr. 3-6, 6-3, 6-2 to advance to the semifinals of the U.S. National Indoor Tennis Championships on Friday.
The top-seeded Nishikori will next play 35-year-old American Michael Russell, who upset third-seeded Lleyton Hewitt of Australia 6-3, 7-6 (6) in another quarterfinal match.
Bogomolov broke Nishikori for a 3-2 lead in the second set only to drop his next two service games and lose the set. In the third, Nishikori fought off three break points to hold serve and broke Bogomolov in consecutive games to take a 5-2 lead.
"Obviously, he was playing really well, I thought," Nishikori said. "He was hitting ball really flat and deep and wasn't making mistakes, especially from the beginning he was very aggressive. I wasn't maybe playing 100 per cent."
Fourth-seeded Lu Yen-Hsun of Taiwan beat American qualifier Alex Kuznetsov 6-1, 6-4 in another match and will next face either Jack Sock or Ivo Karlovic, who play later Friday.
Russell needed nearly two hours to finish off the former world No. 1 Hewitt. He was broken after double-faulting twice while serving for the match at 5-4 in the second set and also failed to convert a couple of match points in the tiebreaker before finally closing it out.
"Every time we play it's a battle," Russell said. "It's kind of the mentality knowing, 'Yeah, you're serving it out. But this guy has a really good return.' And vice versa the same thing when he's serving."
Russell is the second-oldest player ranked in the top 100 behind Tommy Haas, who will turn 36 in April.
He didn't manage a point on his serve while trying to close out the match at 5-4. He then went up 6-4 in the tiebreaker but hit a forehand into the net on his first match point. Hewitt fought off a second match point with a brilliant forehand down the line to level the breaker at 6-all.
But the Australian hit a forehand wide and then a return long to allow Russell to advance to just his third ATP Tour semifinal.
"My rhythm on my serve wasn't there," Hewitt said. "I was feeling my shoulder a little bit and just couldn't hit my spots. So that was putting me under a lot of pressure then, and he makes a lot of balls and makes you play a lot."