Top-ranked Jack Sock loses to fellow American, No. 228 Reilly Opelka at Delray Beach Open

DELRAY BEACH, Fla. -- Top-ranked Jack Sock lost Wednesday night to fellow American Reilly Opelka 4-6, 7-5, 6-3 in the second round of the Delray Beach Open.

The 6-foot-11 Opelka, ranked No. 228, hit 17 aces. With two victories this week, he has doubled his 2017 win total.

No. 6-seeded John Isner hit 30 aces and swept all 18 of his service games but lost to Peter Gojowczyk 7-6 (3), 6-7 (4), 7-6 (5). Isner won only nine points on Gojowczyk's first serve and fell to 1-4 this year.

No. 9 Milos Raonic, the 2017 runner-up, lost to American Steve Johnson 6-2, 6-4. Johnson lost only 12 points on his serve.

American Donald Young, the runner-up in 2015, was eliminated by Evgeny Donskoy 7-6 (6), 6-3.