The 33-year-old switch-hitter initially hurt himself while backing up center fielder Mike Trout on a fly ball in the early innings, then came out in the middle of the fifth, shortly after hitting a deep flyout. Shane Robinson replaced him in left field.
Angels manager Mike Scioscia said Nava "could be" headed to the 15-day DL, which would likely prompt left-handed-hitting outfielder Rafael Ortega, the club's No. 22 prospect per MLB Pipeline, to be recalled.
"I've never had that happen before," Nava said, "and I don't know what to base it off of, if it's serious or not, because I've never experienced anything with my groin."
Nava, signed to a $1.375 million contract over the offseason, recently recovered from tendinitis in his left knee, an ailment that forced him to spend three weeks on the DL. He was starting to find his swing, with five hits over his previous four games.
"It's very frustrating," said Nava, batting .222. "It's not the knee, it's not anything that I was dealing with. So I'm on top of all the other stuff, and then this happens. It's frustrating."
Alden Gonzalez has covered the Angels for MLB.com since 2012. Follow him on Twitter @Alden_Gonzalez and Facebook , and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.