Delray Beach, FL (SportsNetwork.com) - Top-seeded Kevin Anderson was upset by Chinese Taipei's Yen-Hsun Lu in the second round of the Delray Beach Open tennis event on Wednesday.

Anderson, who won this event in 2012 and was last year's runner-up, was surprised by the 61st-ranked player in the world in a 7-6 (8-6), 6-3 final.

Fourth-seeded Ivo Karlovic fired 21 aces before sneaking past 18-year- old Aussie Thanasi Kokkinakis in a pair of tiebreaks, 7-6 (7-4), 7-6 (7-2), on the hardcourts at Delray Beach Tennis Center.

"It was really difficult because he [Kokkinakis] can really hit those forehands, and also it was a little bit windy," said the world No. 29 Karlovic. "I was hanging in there. I was serving really well, and in the tiebreaks I was really good."

Karlovic was the Delray Beach runner-up back in 2010.

Also on Day 3, fifth-seeded Frenchman Adrian Mannarino mauled American wild card Denis Kudla 6-2, 6-2, while seventh-seeded Steve Johnson cruised past Andrey Rublev, 6-3, 6-3 to reach the quarterfinals.

"It was a good thing for me that the conditions were very cold and pretty slow because I was able to move very well on the court, and Denis was missing a little bit more than me," said Mannarino.

The 2015 Delray champion will earn $84,250.