SAN DIEGO -- San Diego Padres third-base coach Matt Williams has been diagnosed with colon cancer and will be away from the team for an undisclosed period of time.

The news was revealed by Padres manager Bob Melvin on Wednesday afternoon, roughly 24 hours before the team begins its highly anticipated season. Williams will be with the Padres for Opening Day festivities when they host the Colorado Rockies on Thursday, then will undergo surgery to remove a growth near his colon on Friday.

Williams, 57, learned about his condition roughly three weeks ago, when a standard physical revealed a low red-blood-cell count that prompted additional testing. He said he feels "as good as I've felt in 20 years."

"I don't have any symptoms, I don't have any issues," Williams said. "At this point it's important now to get it out of there. That's the plan for Friday, and we'll see how it goes from there. They'll test, and they'll do all the pathology and all of that at that point.

"But the initial scans were positive in that on the initial cat scan they didn't see any spread anywhere else. That's a good thing. We'll see where it goes from there."

There is no timetable for Williams' return to the team. Mike Shildt, the former St. Louis Cardinals manager who is with the Padres as a senior advisor, will coach third base in his absence.

A five-time All-Star who was one of the game's best third basemen throughout the 1990s, Williams began his major league career as Melvin's teammate on the San Francisco Giants in the late 1980s, then began his post-playing career on staff with an Arizona Diamondbacks team that Melvin managed from 2005 to 2009.

Shortly after a two-year stint managing the Washington Nationals, Williams served as Melvin's third-base coach with the Oakland Athletics from 2018 to 2019, then joined the Padres for the start of the 2022 season, Melvin's first as their manager.

"He might be the toughest guy I've ever come across in baseball," Melvin said of Williams. "We know, I know in particular, that he's gonna give this the fiercest effort of his life, and he's going to beat it. Our players have been fully supportive of him, but it's hard, being so close to somebody and knowing that he has to deal with it. But I know he is, and I know he's gonna beat it."