Matt Ryan threw for 187 yards and a go-ahead touchdown, while Kroy Biermann returned an interception for a score late in the fourth quarter to seal Atlanta's 20-10 victory over Cleveland.
Delhomme finished the game under center and completed 13-of-23 passes for 97 yards with two interceptions. Wallace was 11-of-15 for 139 yards and a touchdown for the Browns (1-4), who were coming off last week's win over Cincinnati.
Late in the first quarter, Atlanta embarked on a long drive and, thanks to an unnecessary roughness penalty, had a 1st-and-goal at the seven. However, on the first play of the second quarter, Ryan's third-down pass fell incomplete and Matt Bryant kicked a 24-yard field goal.
Joshua Cribbs returned the ensuing kickoff 34 yards to set Cleveland up at its own 44-yard line. The Browns moved quickly down the field, as Wallace completed a 14-yard pass to Mohamed Massaquoi before finding Chansi Stuckey for 18.
Then, on third down from the 19, Wallace threw a short pass to Peyton Hillis on the left side. Hillis stopped the ball with his left hand before catching it as it dropped, and got into the end zone for a 7-3 edge.
Bryant kicked a 30-yarder on the Falcons' next drive, though had a 30-yard try blocked by T.J. Ward later in the half. Cleveland got the ball once more but suffered an injury blow.
Wallace was sacked by John Abraham, who fell on Wallace's right leg as he made the tackle. Wallace hopped off the field on his left leg to be examined, and Delhomme entered for the final few snaps before Cleveland took a 7-6 lead into the break.
Ryan fumbled the ball upon being sacked early in the third quarter, and Kenyon Coleman recovered to set the Browns up at the Atlanta 24.
Cribbs completed a 10-yard pass to fullback Lawrence Vickers on the second play of the drive to give the Browns a 1st-and-goal at the seven. Hillis got the Browns to the two for third down, but couldn't control the handoff on the next play. Fortunately for Cleveland, he recovered and Phil Dawson kicked a 19-yarder.
The field goal was the 234th of Dawson's career, matching Hall of Famer Lou Groza's franchise record.
But the Falcons responded with the go-ahead score. They advanced to the Cleveland 45 when White ran a deep route and got past Sheldon Brown. Ryan hit White with a perfect pass in the end zone as Atlanta grabbed a 13-10 edge with 7:57 left in the third quarter.
After a series of punts, the Browns started a drive at their own 20 with a little over nine minutes remaining. They converted two third downs and faced another at the 47 when Biermann, a defensive end, managed to catch the ball in the backfield. He ran 41 yards into the end zone to push Atlanta's lead to 10 with 4:01 on the clock, and Stephen Nicholas intercepted Delhomme on the Browns' next drive to further secure the outcome.
Hillis finished with 10 carries for 28 yards as well as four receptions for 49 yards, and played through a thigh injury...Abraham recorded two sacks and three tackles for loss...The Browns still lead the all-time series, 10-3. Sunday's game was the teams' first matchup since 2006.