Petersen came on in relief of starter Janson Junk with two outs in the fourth inning and threw just two pitches before he was nailed by a grounder off the bat of Ty France. Marlins catcher Joe Mack gathered the loose ball and threw to first base to record the final out of the inning, but Petersen retreated to the locker room immediately after the play and wasn't available to return for the top of the fifth. Petersen has now made early exits from two of his last five relief appearances, as he was previously lifted from a July 12 contest against the Guardians due to a hamstring injury before getting a clean bill of health coming out of the All-Star break.

The Marlins treated their final game before the All-Star break as a bullpen day, with Tyler Phillips starting and covering the opening frame before Petersen became the third reliever summoned into the contest. After entering with two outs in the top of the fourth, Petersen induced a Travis Bazzana popout to close out the inning. Petersen stayed in the game to begin the fifth and allowed a leadoff home run to Brayan Rocchio, then recorded two outs before exiting the contest after surrendering a base hit to Kahlil Watson. The right-hander may have tweaked the hamstring at some point during the matchup with Watson, but it's not yet known if the injury is severe enough to keep the reliever out following the All-Star break.