DELRAY BEACH, Fla., Feb. 26 (UPI) --
Second-seeded Tommy Haas
of Germany led the group that advanced to the second round of the Delray Beach International Tennis Championships Tuesday.
Haas, who won the Florida tournament in 2006, moved up when his opponent, Igor Sijsling of the Netherlands, retired with an ankle in the second set.
Sijsling pulled up with the match tied 5-7, 6-4. Haas will face Denis Istomin of Uzbekistan in the round of 16.
Istomin advanced by ousting Germany's Benjamin Becker 6-7 (3), 6-4, 7-5.
Jack Sock of the United States advanced with a 6-3, 6-3 victory over Australian Matthew Ebden. Ernest Gulbis of Latvia, who won the Delray in 2010, knocked off American veteran James Blake 6-1, 6-4.
© 2013 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.