John Isner and James Blake looked like the best of friends as they teamed to defeat Marcelo Melo and Jamie Murray 6-4, 6-2 in their first-round doubles match Tuesday night at the Atlanta Tennis Championships.

But on Wednesday they will be on opposite sides of the net when they face off in the second round of the singles portion of the tournament at the Racquet Club of the South in Norcross.

Blake advanced by defeating Ernests Gulbis on Monday. Isner, a former Georgia player and the tournament’s third seed, received a bye.

Their match is scheduled to begin no earlier than 7 p.m. on the Stadium Court. They have never faced each other before.