Tennis: Karlovic rallies past Kyrgios to reach ATP semis

Croatia's 39-year-old Ivo Karlovic blasted 18 aces Friday in a comeback victory over Australian fourth seed Nick Kyrgios to reach the semi-finals of the ATP US Men's Clay Court Championships.

World number 88 Karlovic rallied past 24th-ranked Kyrgios 3-6, 6-2, 6-3 in 92 minutes, advancing to a Saturday matchup against US eighth seed Tennys Sandgren, the world number 56 who beat Argentina's Guido Pella 4-6, 7-5, 6-3 in another quarter-final.

Karlovic won for the first time in five tries against the 22-year-old Aussie, having lost to Kyrgios at last year's Miami and Cincinnati Masters and in 2015 at Kuala Lumpur and the Australian Open.

Two later all-American quarter-finals will send top seed John Isner against sixth seed Steve Johnson and third-seeded Jack Sock against Taylor Fritz.

Karlovic, who has never played Sandgren, seeks his ninth ATP title and second on clay. He won his first tour crown at the 2007 US Men's Clay Courts, downing Argentina's Mariano Zabaleta in the final. His most recent title came at the 2006 Los Cabos Open in Mexico.

Sandgren seeks his first ATP title.