Los Angeles Angels hitting coach Don Baylor broke his right leg while catching a ceremonial first pitch from Vladimir Guerrero on Monday night.

A former Angels outfielder, Guerrero was called upon to kick off the team’s Opening Day festivities by throwing out the ceremonial first pitch to Baylor. However, his errant throw caused Baylor to twist to his right, resulting in a severe injury to his right knee.

Baylor struggled to get to his feet and required assistance from several individuals to exit the field. Guerrero initially thought that Baylor was joking about the injury, ESPN reports.

The 64-year-old coach was taken to a nearby hospital, where he was diagnosed with a fractured right femur, USA Today reports. He is scheduled to undergo surgery on Tuesday.

“Our thoughts and prayers are with Don right now,” Angels manager Mike Scioscia told reporters. “Obviously it’s a freak [injury]. We’ll see how it turns out.”

In 2003, Baylor was diagnosed with multiple myeloma, a type of cancer that affects the bone marrow, ESPN notes. He has since dedicated himself to raise money to fight the disease.

“It got me sick when I was warming up and hearing what happened in the dugout,” Angels outfielder Mike Trout said. The 22-year-old homered in the team’s 10-3 loss to the Seattle Mariners.

A video of Baylor’s freak leg injury can be viewed below.