Bench coach Mark Parent will serve as interim manager in Ventura's absence until he leaves on Friday to attend his son's graduation.
"He called me from the beach this morning, which is nice," Parent said. "He just needs to go and relax and recharge a little bit, enjoy his family a little bit. I'm going to try to do the same thing tomorrow."
Pitching coach Don Cooper will manage the second game of the series on Friday.
"I can't speak for Coop, but for the guys, they know what to expect, how we do things," Parent said. "They're able to hear the suggestions I have for Robin on a daily basis, so they know kind of what I'm about and they know what Coop's about."
Ethan Asofsky is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.