The Red Sox got some badly needed reinforcements ahead of Wednesday’s game when Tyler O’Neill was activated from the injured list. Catcher Tyler Heineman was optioned to Triple-A to clear a spot on the active roster.

O’Neill, who had been one of Boston’s best hitters early before slumping throughout May, missed nine games due to right knee inflammation but will bat fifth and start at right field in his return to action. He’ll line up alongside Jarren Duran in left field and Ceddanne Rafaela in center, with Rob Refsnyder serving as the designated hitter.

Having O’Neill back will help stabilize things after rookie Wilyer Abreu was placed on the IL with a sprained ankle Tuesday, but the Red Sox are still patching things together for the time being. Enmanuel Valdez, recently promoted from Triple-A after Vaughn Grissom and Romy Gonzalez both got hurt, is starting at second base and batting second. Refsnyder is batting third, and shortstop David Hamilton is batting seventh. Reese McGuire will catch and bat ninth.

Nick Pivetta (2-4, 4.08) is scheduled to take the mound for the Red Sox, and he will face off against Atlanta’s Spencer Schwellenbach (0-1, 5.40) as the club aims to salvage a two-game split against the NL East powerhouse.

Red Sox lineup

Jarren Duran LF

Enmanuel Valdez 2B

Rob Refsnyder DH

Rafael Devers 3B

Tyler O’Neill RF

Dominic Smith 1B

David Hamilton SS

Ceddanne Rafaela CF

Reese McGuire C

Nick Pivetta P

How to watch

When: 1:35 p.m.

Where: Fenway Park, Boston

Broadcast info: NESN, WEEI 93.7 FM, WCCM 1490 AM (Spanish)