Wild card entrant Jack Sock posted the upset of the day at Atlanta Open as he downed seventh seeded Alex Bogomolov Jr.  6-2, 4-6, 6-4 in the first-round match on Monday.

Sock will next face Steve Johnson, who arrowed 10 aces and saved 10 of 12 break points to dismiss Donald Young challenge with 6-3, 3-6, 6-3 victory. This win came as first ATP tour level victory for Johnson.

In other match of the day, fifth-seeded Kevin Anderson of South Africa survived all three break points to beat Italian Paolo Lorenzi 6-4, 6-3.

Also, Luxembourg’s Gilles Muller arrowed 14 aces against Australian Marinko Matosevic and defeated him 7-6(5), 6-4.