The towering American edged Kevin Anderson in a final of three tie-breaks to win the BB&T Atlanta Open last week.
And the eighth seed again proved he can go the extra mile as he defeated Alex Kuznetsov 7-6 (7/2) 7-6 (7/4) at the at William HG FitzGerald Tennis Center.
Joining him in the third round is Mardy Fish, who defeated France's Julien Benneteau 6-3 7-5.
Elsewhere, Croatia's Ivan Dodig was a 2-6 6-2 6-3 conqueror of Germany's Tobias Kamke, the Czech Republic's Radek Stepanek eased past France's Michael Llodra 6-2 6-1, while Russia's Dmitry Tursunov ousted France's Gilles Simon 6-4 6-2.
In the second round of the women's competition, Andrea Petkovic beat fellow German Mona Barthel 6-2, 6-2.