The Boston Celtics signed guard Kelvin Upshaw Thursday to a 10-day contract to replace center Ramon Rivas, who was placed on the injured list due to back spasms.

Upshaw, 26, from the University of Utah, played this season for the Albany Patroons of the Continental Basketball Association and the Miami Heat of the National Basketball Association.The 6-foot-2 guard was waived by Miami on Jan. 31 after averaging 6.3 points in nine games. He will wear No. 7 for the Celtics.

The moves mean the Celtics still have the maximum 12 players on the roster, so another roster move would have to be made when star forward Larry Bird comes off the injured list.