The White Sox will be without manager Tony La Russa indefinitely due to an unspecified medical condition, the team announced Wednesday.

On Tuesday, the 77-year-old Hall of Famer’s absence at the direction of doctors came as a surprise less than an hour before first pitch against the Royals.

“Following a medical evaluation [Wednesday] morning, Chicago White Sox Manager Tony La Russa now is scheduled over the coming days to undergo additional testing in Arizona by his personal physicians,” the team said in a statement. “His absence from the club will be indefinite pending the results of these evaluations.”

Bench coach Migel Cairo will assume managerial duties in La Russa’s absence.

“It’s unbelievably tough,” outfielder Andrew Vaughn said. “We really don’t have much information on what’s going on.

“We were trying to figure out what was going on. They mentioned a few things, maybe his heart, or something like that.”

The White Sox have lost five straight amid a disappointing season in which they were viewed as World Series contenders. They entered Wednesday’s game against the Diamondbacks with a 63-66 record, six games behind the Guardians in the AL Central and 7 1/2 games out of the third and final American League wild-card spot.