CHICAGO -- Outfielder Angel Pagan remained sidelined with back stiffness as the San Francisco Giants opened a two-game inter-league

series against the Chicago White Sox on Tuesday.

Pagan missed his third straight game and recovery is going slower than hoped, Giants manager Bruce Bochy said prior to the game at U.S.

Cellular Field.

"Right now he's a day-to-day," Bochy said. "He's making a little progress but not as much as we'd have hoped."

The 32-year-old veteran was batting .307 through 63 games before sitting out the final two games of a series with Colorado.

"He did have an MRI and it showed some inflammation in there, but nothing structurally," Bochy said. "It's just a matter of getting it

calmed down."

There are no current plans to put Pagan on the disabled list.

The Giants had better news with catcher Buster Posey, in the lineup as designated hitter. He took a foul tip off his mask in the fourth inning

and left Sunday's game as a precaution.

Bochy said Posey was available to catch on Tuesday and it looked like a possibility when Hector Sanchez, behind the plate in Posey's

place, was clipped by Adam Dunn's bat in the fourth. Sanchez was okay and stayed in the game.