Lincoln native Jack Sock advances to the quarterfinals of the Atlanta open.
Sock, a 7-6 (5), 7-6 (5) winner over Steve Johnson in a matchup of wild cards, advances to take on the No. 1 seed John Isner.
Isner knocked of Ruben Bemelmans of Belgium 4-6, 6-3, 6-
In other quarterfinal matches Friday, No. 4 seed Andy Roddick
faces Michael Russell and No. 3 seed Kei Nishikori of Japan plays countryman Go Soeda, the No. 8 seed.