Fourth-seeded Milos Raonic of Canada won his first match since the Australian Open, beating the United States' Tommy Paul 7-6 (6), 6-4 on Tuesday in the first round of the Abierto Mexicano Telcel in Acapulco, Mexico.
Raonic's most recent match had been a fourth-round loss in Melbourne to Serbia's Novak Djokovic, who went on to win the Grand Slam event.
Raonic racked up 13 aces and 10 double faults while Paul had one ace and four double faults.
Elsewhere in the first round, Italy's Lorenzo Musetti upset third-seeded Diego Schwartzman of Argentina 6-3, 2-6, 6-4, but top-seeded Stefanos Tsitsipas of Greece and sixth-seeded Fabio Fognini of Italy won in straight sets. Also posting wins were the Netherlands' Tallon Griekspoor, the United States' Frances Tiafoe and Great Britain's Cameron Norrie.
Dubai Duty Free Tennis Championships
South Africa's Lloyd Harris defeated top-seeded Dominic Thiem of Austria 6-3, 6-4 in the second round at Dubai, United Arab Emirates.
Thiem never managed a break point in the match as Harris won 29 of his 30 first-serve points.
Fifth-seeded David Goffin of Belgium, sixth-seeded Pablo Carreno Busta of Spain and 12th-seeded Daniel Evans of Great Britain also fell in the second round.
Second-seeded Andrey Rublev of Russia, third-seeded Denis Shapovalov of Canada, fourth-seeded Roberto Bautista Agut of Spain, eighth-seeded Karen Khachanov of Russia, 11th-seeded Dusan Lajovic of Serbia, 13th-seeded Hubert Hurkacz of Poland, 14th-seeded Filip Krajinovic of Serbia, 15th-seeded Taylor Fritz of the United States, 16th-seeded Jannik Sinner of Italy, 17th-seeded Lorenzo Sonego of Italy all advanced.
--Field Level Media