Nunez strained his right hamstring while beating out an infield single last Saturday at Detroit. The move was made retroactive to Sunday.
With right-hander Yohan Pino scheduled to make his major league debut Thursday against Chicago, the Twins needed to make room on the 25-man roster. To clear space on the 40-man roster, right-hander Mike Pelfrey was transferred to the 60-day disabled list.
Nunez's injury left the Twins with only three bench players for the time being. He's batting .290 with two homers and 11 RBIs in 25 games.
Pino went 9-1 with a 1.92 ERA and 61 strikeouts in 61 innings for Triple-A Rochester.