SAN DIEGO -- Yasmani Grandal didn't think anything was out of the ordinary Thursday when he wasn't in the starting lineup for Triple-A Tucson.

But the 23-year-old catcher was a little suspicious when he wasn't even called upon to pinch-hit during the game.

"I kept waiting for the call and it never came," Grandal said.

His trepidation was eased when Tucson manager Terry Kennedy pulled Grandal aside after the game to tell him he was headed to San Diego to join the Padres.

On Friday, the Padres added Grandal to their 25-man roster to give them an additional position player and a switch-hitter to use either as a starter or off the bench.

To make room for Grandal on the 40-man roster, the Padres on Friday designated pitcher Jeff Suppan for assignment.

Grandal, 23, was hitting .317 with a .421 on-base percentage and four home runs, 23 RBIs in 120 at-bats with Triple-A Tucson, the Padres' top Minor League affiliate. He is the Padres' third-ranked prospect and the fifth-best catching prospect in all of baseball, according to MLB.com.

"A switch-hitter who has some pop in his bat," Padres manager Bud Black said. "He gives us an extra bat until [Mark Kotsay] gets back. He'll be able to supplement our bench."

Grandal was one of four players that the Padres obtained from the Reds in the December deal that sent pitcher Mat Latos to the Reds. Grandal joins two of those players in San Diego, pitcher Edinson Volquez and first baseman Yonder Alonso.

A switch-hitter, Grandal was hitting .242 right-handed and .345 left-handed, with all of his home runs coming from that side of the plate. Grandal has been swinging the bat well lately for Tucson, hitting .357 in his past 10 games before the promotion.

He missed some time in April with a right hamstring strain.

The Padres already have two catchers on the roster in Nick Hundley and John Baker. It's conceivable the team could carry three catchers, as Interleague Play begins on June 12. For the time being, Grandal will give the team some at-bats off the bench.

Black said Grandal has shown a lot of improvement on the defensive side. He was aided by Kennedy, a former Major League catcher, while with Tucson. He also received a lot of instruction in Spring Training from Brad Ausmus, a former catcher as well.

"TK [Kennedy] said he was doing a lot of good things," Black said. "He's got a pretty good fundamental skill set."