Kevin Anderson has advanced into the fourth round of the French Open after Croatian opponent Ivo Karlovic was forced to retire at the end of the first set.

A back problem troubled Karlovic throughout the third-round encounter and he was forced to admit defeat after losing the first set 6-3 against his South African opponent.

Anderson twice had break points in Karlovic's opening two service games, but the set remained on serve until 3-4 when Anderson eventually broke to take control of the contest.

The South African took the set on his third break point, but that proved to be the conclusion of the match as Karlovic bowed out.