Sock missed much of last year with a thumb injury and made the tournament as a wild card. His eyes welled with tears after his first win of 2020. Top-seeded Nick Kyrgios withdrew before his first match because of a lingering right arm injury.
No. 2-seeded Milos Raonic won 96% of his first-serve points and defeated Denis Istomin 6-2, 6-2. No. 4 Reilly Opelka hit 20 aces and rallied past qualifier Ernests Gulbis 6-7 (5), 6-4, 7-6 (4).