The thrill of opening night took a somber turn for the San Francisco 49ers on Monday night, and they could be without their new backup running back for some time.

Reggie Bush limped off the field and was then carted to the locker room in the first half of Monday's game at Levi's Stadium against the Minnesota Vikings, the final game of Week 1.

The team only disclosed that Bush had a leg injury and said his return was questionable, according to the broadcast on ESPN.

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Bush, 30, is entering his 10th season in the league. After playing the past two seasons for the Detroit Lions, Bush signed a one-year deal worth $1.6 million this past offseason.

The 49ers let longtime starter Frank Gore go after last season, elevating second-year back Carlos Hyde into the starting spot with the speedier Bush as the backup / change-of-pace option.