One of the most important players on MLB's top team could be out for a while.

San Francisco Giants first baseman Brandon Belt sustained a fractured thumb after getting hit in the hand by a pitch on Sunday, the team announced per MLB.com. After further evaluation, Andrew Baggarly of The Athletic reports the prognosis is Belt's thumb will need around four weeks to heal, with further time potentially needed to reach playing shape. That would conceivably keep out Belt until at least the World Series, if the Giants reach that far.

The Giants have since placed Belt on the 10-day IL, ending his regular season.

Belt's injury occurred when he squared up to bunt and was hit by an inside 93 mph fastball from Colorado Rockies reliever Lucas Gilbreath.

If Belt really is out for nearly all of the playoffs, that would be a big loss for the Giants.

Like many players on the team, the 33-year-old Belt is finishing up a career year at the plate with a .274/.378/.597 line and 29 homers in 97 games. He's also regarded as one of the team's most important players, to the point that he wore a makeshift "C" on his jersey during a game.

Thumb fractures are a significant injury for power hitters like Belt, with players often missing weeks due to the injury and taking even longer to return to 100 percent at the plate. That's not ideal when the Giants are about to enter the playoffs for the first time since 2016 and would very much like to have their best players for a Game 163, wild-card game and/or NLDS.

For now, the 102-54 Giants will have to worry about finishing up the regular season without Belt. The team currently holds a two-game lead over the Los Angeles Dodgers in the NL West with six left to play in the season.