BOSTON -- The A's on Monday conceded that Daric Barton's strained left hamstring is worse than expected, and a stint on the disabled list is more than likely.

If that's the direction in which Oakland goes, Triple-A infielder Tommy Everidge appears to have a shot at making his big league debut this week.

Everidge, who hit two homers in a 12-inning victory for Triple-A Sacramento on Sunday and went 2-for-4 on Monday to raise his batting average to .382, has played first and third base during his 42-game stint with the River Cats.

Barton, who took over as Oakland's primary starting first baseman when veteran Jason Giambi was placed on the DL with a strained right quadriceps on July 20, tweaked his left hammy while stretching to receive a throw on Sunday at Yankee Stadium.

He stayed in the game for a couple of innings but was lifted for a pinch-runner after hitting an eighth-inning double. Upon arriving at Fenway Park for the opener of a four-game series against the Red Sox, Barton made it clear wasn't ready to play.

"We just talked about it," manager Bob Geren said. "We're discussing all options at this point."

Barton, batting .147 in 17 games with Oakland this season, was replaced in the starting lineup on Monday by Bobby Crosby. Nomar Garciaparra and backup catcher Landon Powell also have spent time at first base this season.

Everidge, 26, was a 10th-round pick of the A's in the 2004 First-Year Player Draft. A 6-foot, 244-pound right-handed hitter out of Glen Ellen, Calif., he has nine home runs, 14 doubles, a triple and 31 RBIs, with a .424 on-base percentage and a 1.059 OPS.

Everidge isn't on Oakland's 40-man roster, however, so the A's would have to make a corresponding move were they to promote him.