ATLANTA (AP)—Mardy Fish took a hit in his gradual return to full-time tennis Wednesday night in the Atlanta Open, falling 4-6, 6-2, 7-5 to Michael Russell in a rain-delayed first-round match that began Tuesday.

It was only Fish's fourth match since the U.S. Open in September when he withdrew before a fourth-round match against Roger Federer because of an irregular heartbeat.

Ranked No. 13 in the world last July, the sixth-seeded Fish — the Atlanta Open winner in 2010 and '11 — fell to 1-3 this season. He's ranked No. 63 after his first match since losing in a lower-level ATP Challenger tournament in April.

Fish was unavailable for comment after the match.

''I thought he played really well,'' said the 35-year-old Russell, ranked 85th. ''He was coming up with 130 mph serves. I couldn't tell. Usually when somebody takes four months off, they're a little rusty. But I thought it was really good tennis.''

Russell took advantage of the delay to make racket adjustments.

''It definitely helped me a little bit,'' Russell said about the delay. ''I was able to change my string tension. I was pleased with the rain delay.''

Seventh-seeded Lleyton Hewitt advanced to the quarterfinals with a deceivingly difficult 7-6 (6), 6-4 win over wild-card entry Rhyne Williams. The 32-year-old Hewitt, 64th in the world, trailed 2-6 in the tiebreaker before winning six straight points, and only broke serve in the second set in the deciding game.

While Hewitt and Russell held serve for the older guard, 19-year-old Chrisitian Harrison won his first match in an ATP main draw. A wild-card entry, the 373rd-ranked Harrison beat Alejandro Falla 6-1, 6-7 (7), 6-2.

''I think whenever I got in position to win the second set, I got a little hesitant,'' Christian said. ''I kind of let the nerves show a little bit. I just believed in myself in the third. I've worked really hard . . . to make sure that when it's hot or humid I'm the fitter one. Whenever I could see that (Falla) was getting tired, I tried to move him more.''

Harrison will play top-seeded John Isner in the second round. Isner and second-seeded Kevin Anderson have yet to play.