World number four Dominic Thiem of Austria missed a chance to reach a career-best third in the ATP rankings with a Rio Open quarterfinal loss Saturday to Italy's Gianluca Mager.
Mager, a 128th-ranked qualifier playing in only his eighth career tour-level match, defeated 2017 Rio champion Thiem 7-6 (7/4), 7-5 in a match that was halted on Friday by rain.
Had Thiem reached the semifinals in his 2020 clay-court debut, he would have overtaken Roger Federer for third in Monday's ATP rankings.
Thiem was down a set and a break when rain stopped the match Friday with Mager leading 7-6 (7/4), 2-1.
Mager served for the match in the ninth game of the second set but Thiem broke to pull level at 5-5, only to have the Italian claim the final two games and the match after one hour and 55 minutes on the court.
Mager booked a semifinal date later on Saturday against the winner of another rain-halted Friday match between 133rd-ranked Spanish qualifier Pedro Martinez and Hungary's 106th-ranked lucky loser Attila Balazs.
Martinez led Balazs 6-2, 2-2 when play was stopped.
Saturday's other semifinal pits Chilean third seed Cristian Garin and fifth-seeded Borna Coric of Croatia.