MEMPHIS, Tenn. -- Ivo Karlovic moved into the second round of the Memphis Open with a 7-6 (7), 6-3 victory over Lukas Lacko on Tuesday.
Sam Querrey also advanced to the second round by upsetting No. 7 seed Benjamin Becker 4-6, 6-2, 6-1. Querrey, the 2010 champion, won his first match of the year after opening with three losses.
"After I lost the first set, I said I'm going to do whatever it takes to grind through this," Querrey said. "I went out and put balls in play and played defense. It feels good to get through it."
Also advancing were Bernard Tomic, who defeated Igor Sijsling 4-6, 6-3, 6-2, and Americans Ryan Harrison, Austin Krajicek and Denis Kudla, all of whom qualified for the tournament. Sixth seed Steve Johnson moved into the second round with a 6-3, 6-3 win over Filip Krajinovic.
Harrison next plays top seed and two-time defending champion Kei Nishikori of Japan, who had a first-round bye. Nishikori is ranked fifth in the world.
Harrison defeated Malek Jaziri 7-6 (1), 7-6 (3) for his fourth win in four days. He played three qualifying matches to earn a spot in the main draw.
Harrison will be playing a top-five opponent for the 13th time in his career. He is 0-12 against top-five opposition.
"It's going to be a great opportunity to see how I compete," Harrison said. "I'm looking forward to the challenge."
Karlovic, runner-up in this tournament a year ago, had 23 aces to overpower Lacko, who had a set point in the opening-set tiebreaker but failed to convert. Karlovic won the first set when Lacko netted a forehand.
In the second set, Karlovic broke Lacko for the only time in the match to take a 5-3 lead. Karlovic then served a love game with two aces and two service winners to advance.