Beckham, the top pick in the 2008 draft, made his major-league debut in September, and has earned praise from manager Joe Maddon.
Though Beckham, 23, would have been a longshot to make the opening day roster, he was likely to see action during the season if the Rays needed depth or had an injury to a middle infielder.
Beckham was promoted after a solid season at Triple-A Durham, hitting .276 with four homers, 51 RBIs and a .342 on-base percentage. He was chosen by the Rays ahead of Pedro Alvarez, Eric Hosmer and Buster Posey, among other present-day major-league stars.
The knee injury is the latest setback in Beckham's career, as he has progress has been slowed by inconsistent play and a drug-related suspension. Beckham was believed to have been hurt working out, but no details were available.
Hak-Ju Lee, the Rays other top middle infield prospect, is recovering well from knee surgery after being injured last season, but his status for the start of the 2014 season is uncertain.
