NEW YORK - AUGUST 26: Ivo Karlovic of Croatia serves against Jan Minar of Czech Republic during Day 2 of the 2008 U...

NEW YORK - AUGUST 30: Sam Querrey of the United States waves to the crowd after defeating Ivo Karlovic of Croatia during Day 6 of the 2008 U.S. Open at the USTA Billie Jean...

Roger Federer, of Switzerland, walks off the court after he was upset by Ivo Karlovic, of Croatia, in a tennis match at the Western & Southern Financial Group Masters tennis tournament, Thursday...

HAMBURG, GERMANY - MAY 15: Novak Djokovic of Serbia returns during the match against Ivo Karlovic of Croatia during day four of the Tennis Masters Series Hamburg at Rothenbaum Tennis Centre on...

Swiss Roger Federer returns the ball to Croatian Ivo Karlovic during their ATP Tennis Open in Rome on May 8, 2008. AFP PHOTO / Christophe Simon (Photo...

TOKYO - OCTOBER 04: Ivo Karlovic of Croatia serves against Hyung-Taik Lee of Korea during Day 4 of the AIG Japan...

Andy Roddick returns a shot against Ivo Karlovic of Croatia in a match at the Legg Mason Tennis Classic, Saturday, Aug. 4, 2007, in...

The ace count went to opponent Ivo Karlovic, but the match went to Andre Agassi on Thursday at the U.S. Open

Ivo Karlovic is the tallest man on the ATP Tour

Croatia's Ivo Karlovic casts a long shadow in the late evening sun as he serves during his second-round...

Defending champion Lleyton Hewitt didn't have an answer on how to stop 6-foot-10 Ivo Karlovic, falling in four sets at Wimbledon

Ivo Karlovic had 18 aces and 41 service winners in Monday's victory over Lleyton Hewitt