The 2023 baseball season is just a day old, but the blood is already boiling in southern California.

After his team's 2-1 loss to the Oakland Athletics, the Los Angeles Angels' Anthony Rendon was caught on camera gripping an A's fan by his shirt and swinging an open hand toward the fan's head.

It's unclear exactly what sparked the confrontation, but Rendon claimed the fan called him a b----.

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Anthony Rendon

Anthony Rendon of the Los Angeles Angels during a game against the Oakland Athletics at RingCentral Coliseum Oct. 4, 2022, in Oakland, Calif.  (Lachlan Cunningham/Getty Images)

"What'd you say? You called me a b----, huh. Yeah you did. Yeah you did. Yeah motherf----," Rendon told the fan while gripping his shirt.

That's when Rendon let go of his grip and then tried to swipe at the fan's A's hat.

Angels teammate Mike Trout stopped in his tracks to witness the war of words, but everyone walked away before things got worse.

Rendon on opening day

Anthony Rendon of the Los Angeles Angels, right, fist-bumps coaches and teammates during a game against the Oakland Athletics at RingCentral Coliseum Thursday, March 30, 2023, in Oakland, Calif.  (Suzanna Mitchell/MLB Photos via Getty Images)

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MLB said it is investigating the incident.

"We are aware of the video, and we are now looking into the matter," MLB said in a statement.

Rendon didn't make contact on the swipe, so fans were quick to take their own jabs at Rendon, who has struggled to stay healthy since signing his seven-year, $245 million deal in 2019. He hasn't exactly performed well when he has played, hitting .250 with a .776 OPS in 158 games since joining the Angels.

The Angels led 1-0 in the bottom of the eighth after six scoreless innings and 10 strikeouts by Shohei Ohtani, who also batted 1-for-3 with a walk, and a highlight reel catch by Hunter Renfroe. 

Anthony Rendon in Oakland

Anthony Rendon of the Los Angeles Angels before a game against the Oakland Athletics at RingCentral Coliseum Oct. 4, 2022, in Oakland, Calif.  (Lachlan Cunningham/Getty Images)

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But the bullpen allowed two runs in the frame, and the offense couldn't get back on the board.