Frank Mason III will be sidelined an additional four-to-six weeks with a partial tear of the right plantar fascia, the Kings announced on Thursday.
An MRI conducted on Wednesday in Sacramento revealed the injury.
Mason, 23, had spent more than a week getting treatment for the injury, which was originally thought to be a heel contusion suffered at the end of the first quarter on Dec. 31 against the Memphis Grizzlies.
The team said the rookie from Kansas will be reevaluated 4-6 weeks from the date of the original injury.
Mason was selected in the second round, 34th overall, in the 2017 NBA Draft and has appeared in 29 contests for Sacramento, posting averages of 7.6 points, 2.1 rebounds, 2.9 assists and 18.9 minutes per game.
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