Peterson hit the first pitch from Brandon Kintzler (0-1) toward the gap in left-center field. Left fielder Ryan Braun and center fielder Carlo Gomez didn't bother to field the ball as Callaspo scored and Braves players raced out of the dugout to swarm Peterson near second base.
With one out in the 11th, Kintzler walked Callaspo. Andrelton Simmons' sharply hit grounder hit third-base umpire Chad Fairchild and bounced into left field. Runners advanced to second and third on pinch-hitter Eric Young Jr.'s grounder to Kintzler.
Luis Avilan (2-0) pitched the last 1 1/3 innings for Atlanta, including getting a double-play with runners at first and third to end the 10th.