Andy Roddick of the United States returns a volley to Mardy Fish of the United States during the semi-finals of the Atlanta Tennis Championships in Johns Creek, Georgia July 24, 2010. Fish defeated Roddick 2-0 to advance to the finals. [Xinhua/Reuters Photo]

Mardy Fish shocked top seed Andy Roddick 7-6 (7-5), 6-3 on Saturday to set up a final clash with fellow American John Isner at the ATP Atlanta Championship.

Sixth seed Fish snapped a seven-year drought against Roddick, his former roommate during their teenaged years in Florida. The number 49 Fish beat his mate in 2003 in their first ATP clash. Since then, Roddick had won nine in a row.

Fish needed only one break to secure victory over Roddick, firing nine aces and 27 winners.

Isner, seeded second, struggled in the heat against Kevin Anderson to win 6-3, 6-7 (7-9), 6-3.

Fish beat Isner in their only prior meeting, last season indoors.

Isner, winner of the longest match in tennis history less than a month ago at Wimbledon, will be playing in his fourth final of the season. He owns a title at Auckland while missing out in Memphis and Belgrade.