LOS ANGELES -- The 30-man Opening Day roster that the Dodgers submitted on Thursday changed before they even got to the opener.

Dustin May, Los Angeles' No. 2 prospect per MLB Pipeline, was initially optioned to the team's alternate training site, only to be recalled hours later to start Opening Night against the Giants when scheduled starter Clayton Kershaw injured his back and went on the injured list.

Manager Dave Roberts said May was given the start because he had been stretched out to back up Walker Buehler, whose Summer Camp buildup was behind schedule. May was given a heads-up that he might start on Wednesday, when his simulated game was scratched.

May’s brief demotion wasn’t the only Thursday morning surprise, as the Dodgers included speedy outfielder Terrance Gore on their roster. Gore gives Los Angeles a baserunning specialist to utilize for the new rule that starts extra innings with an automatic runner on second base.

The Dodgers are carrying 16 pitchers and 14 position players on their 30-man roster. The large number of pitchers is partly to mitigate the late arrival to Summer Camp of relievers Scott Alexander, Pedro Báez and Kenley Jansen. Alexander, coming off left hand surgery, made the squad despite not pitching in any Summer Camp game. He threw a simulated game on Thursday.

Los Angeles will open with four left-handed relievers -- Alexander, Adam Kolarek, Caleb Ferguson and newly signed Jake McGee -- despite a new three-batter rule that minimizes the relevance of a situational left-hander.

The 30-man roster must be reduced to 28 on Aug. 6 and to 26 on Aug. 20.

Pitchers (16): Scott Alexander, Pedro Báez, Walker Buehler, Caleb Ferguson, Dylan Floro, Brusdar Graterol, Kenley Jansen, Adam Kolarek, Joe Kelly, Dustin May, Jake McGee, Dennis Santana, Ross Stripling, Blake Treinen, Julio Urías, Alex Wood

Catchers (2): Austin Barnes, Will Smith

Infielders (6): Matt Beaty, Max Muncy, Edwin Ríos, Corey Seager, Chris Taylor, Justin Turner

Outfielders (6): Cody Bellinger, Mookie Betts, Terrance Gore, Enrique Hernández, Joc Pederson, AJ Pollock