TUCSON, Ariz. -- Giants infielder Kevin Frandsen faces the possibility of missing the entire season after suffering what is believed to be a ruptured left Achilles tendon Monday in a Minor League exhibition game at Scottsdale, Ariz.

Frandsen was testing his leg after being sidelined since March 16 with tendinitis. Manager Bruce Bochy, who accompanied the Giants here for their 6-5 exhibition loss to the Arizona Diamondbacks, was told that Frandsen had singled and was rounding second base on his way to third when he hurt himself.

Frandsen's expected to undergo a magnetic resonance imaging examination Tuesday to confirm the severity of the injury. Bochy said that Frandsen will be sidelined for five to six months if he's hurt as badly as is believed.

"I'm sure that's tough for the kid's psyche, to have to deal with this, if this is the case," Bochy said. "But Kevin's not going to let up. He'll be back."

Frandsen, 25, had endured a luckless spring even before Monday. Considered a contender with Ray Durham for the second-base job when Spring Training began, Frandsen was moved to shortstop when Omar Vizquel tore a meniscus in his left knee and required surgery. But Frandsen's performance at shortstop was deemed ineffective, prompting the Giants to announce on March 6 that he'd no longer be playing there.

Frandsen still had a place on the Opening Day roster, since the Giants considered him an essential utilityman capable of playing second base, third base and the outfield. Now, Saturday's acquisition of infielder Jose Castillo on waivers from Florida looks like a wise move, especially since the Giants might have to search for another spare infielder.

"Castillo looks like he'll play a bigger role," Bochy said. "We were a little thin anyway. We're fortunate we have him."

Frandsen's injury also carried emotional impact. A San Jose native who grew up rooting for the Giants, Frandsen had established himself as one of the team's scrappiest, most popular players.

First baseman Dan Ortmeier, one of Frandsen's best friends on the club, looked glum as he spoke.

"My thoughts and prayers to go him and his family," Ortmeier said. "I know he's going to take it pretty hard. Good buddy, good teammate, good guy in the locker room -- what can you say?"

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When Frandsen's tendinitis was diagnosed, he revealed that his left foot had bothered him since early in the exhibition season. But with his playing status at stake, he competed anyway. Frandsen rested completely for a few days after that March 16 game and recently resumed taking batting and fielding practice. The Giants did not appear worried that they were rushing Frandsen back into action, and Frandsen himself was eager to return to the field. Bochy said that Frandsen would have started in Tuesday's Cactus League finale against the Chicago Cubs had he emerged healthy Monday.

"There was no debate regarding whether he was ready," Bochy said. "That's why we put him in the Minor League game, so he could take it easy, if necessary."

Before Frandsen's injury occurred, the Giants reassigned infielder Ryan Rohlinger to Minor League camp. Rohlinger became expendable after Castillo's arrival and probably won't return even with Frandsen sidelined.

In other injury-related news, Bochy said that right-hander Kevin Correia, who was scratched from Monday's start, threw off a bullpen mound in Scottsdale and will be re-evaluated Tuesday.