Unseeded Nick Kyrgios moved into the second round of the Italian Open by beating 12th seed Daniil Medvedev.
Australian Kyrgios, who produced underarm serves on a number of occasions, including the first point of the match, won 6-3 3-6 6-3 in Rome.
Medvedev received on-court treatment for a lower back injury before the second set and later smashed a racquet on the ground in frustration.
Kyrgios, who ended the match with four aces, plays Norway’s Casper Ruud next.
It was not the first time Kyrgios, 24, has served underarm this season – he used similar tactics during a second-round win over Rafael Nadal at the Mexican Open in February.
Seventeen-time Grand Slam champion Nadal criticised Kyrgios after that match, saying the Australian “lacks respect for the public, the rival and himself”.
Kyrgios also twice served underarm during his 6-3 6-1 win over Serb Dusan Lajovic at the Miami Open in March, with former British Fed Cup captain Judy Murray saying Kyrgios was a “genius” for disrupting his opponent’s game.