After leaving Friday's game with symptoms related to a concussion he sustained earlier last week, it will be some time before Brandon Belt returns to the San Francisco Giants.

Belt, who sustained head and neck injuries after colliding with a player's knee while sliding into second base last Tuesday, was forced to leave the Giants' game early on Friday due to lingering symptoms stemming from the incident.

The Giants are now unsure if the 27-year-old first baseman will return by the end of the season.

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"He said he felt a little weird [Friday], then it got a little worse in the game," manager Bruce Bochy said. "It's a little hard to figure out how long to take. Obviously you want to be cautious, but how cautious? When he passed all the tests, he was cleared to play. Now he's got to be cleared to play again. Until he is, he won't play."

The Giants have experienced slow returns from concussions this season, most recently with left fielder Nori Aoki, who has been experiencing symptoms for nearly six weeks after being hit in the helmet with a fastball in August.

In his fifth season in the majors, Belt is hitting .280/.356/.478 with 18 home runs and 68 RBI.

(h/t San Jose Mercury News)