SPLIT, Croatia (AP) Mario Ancic says he has retired from professional tennis because his body would not allow him ``to continue on a high level.''

The 26-year-old Croat said Wednesday it was ``one of the toughest decisions I ever had to make.''

Ancic first came to prominence in 2002 in his Grand Slam debut at Wimbledon, where he defeated seventh-seeded Roger Federer in the opening round.

Ancic reached a career-high ranking of No. 7 in 2006, two years after he reached the Wimbledon semifinals for his best Grand Slam result.

However, he suffered from mononucleosis in 2007 and lately has struggled with a back injury.