Santiago Casilla goes on DL

San Francisco Giants reliever Santiago Casilla was placed on the 15-day disabled list and reportedly may miss up to four weeks with a right hamstring strain after he was injured while trying to beat out a throw for a hit on Wednesday night.

Casilla suffered a Grade 2 strain while running out a ground ball in the ninth inning of Wednesday night's 5-1 win over the Rockies and may miss up to four weeks, the San Jose Mercury-News reported Thursday.

Casilla stumbled over first base and fell to the ground in pain. He was helped off the field.

Just moments before in the dugout, Bochy had told Casilla to not even bother swinging -- just take it easy at the plate.

"I was shocked he was running like that," Bochy said. "Guess he thought he had a hit. I don't know what got into him. Never seen him run like that."

Casilla had an MRI on Wednesday night but manager Bruce Bochy said the results were not back.

Meanwhile, Giants starter Matt Cain, who also tweaked his hamstring Wednesday, was diagnosed with a Grade 1 strain but hasn't been ruled out for his next start, the Mercury-News reported. He will get treatment for a few days.

The Giants recalled George Kontos from Triple-A Fresno to take Casilla's spot on the roster. He pitched in one game for the Giants before being optioned to Fresno on May 10. He is 0-2 with a 3.80 ERA in 14 games with the Grizzlies this season.

The Associated Press contributed to this report.