BOSTON -- Red Sox second baseman Dustin Pedroia is expected to miss roughly six weeks with a fractured left navicular bone in his left foot that he suffered on Friday in San Francisco, the club's medical staff confirmed on Monday.

That means that Pedroia could return to the Red Sox during the early portion of August. Team medical director Thomas Gill examined Pedroia on Monday, and confirmed the non-displaced fracture that was diagnosed by doctors in San Francisco. Gill added that Pedroia is not expected to need surgery.

Meanwhile, Dr. Gill also got a closer look at Victor Martinez, and determined that the catcher has a minimally displaced fracture on the tip of his left thumb. Though the club wouldn't say if Martinez will go on the disabled list before Tuesday's game against the Rays, that certainly seems like a strong possibility, given the nature of the injury, which occurred when Martinez was hit by multiple foul tips on Sunday against the Giants.

Martinez isn't expected to need surgery, and the club didn't give a timetable on his return to action.

Jason Varitek, a three-time All-Star, will take over the bulk of catching duties as long as Martinez is out. Complicating matters as to who will back Varitek up is that both of the club's most seasoned Minor League catchers -- Mark Wagner and Dusty Brown -- are injured.

As for the third member of the Red Sox who was injured over the weekend in San Francisco, the news sounds optimistic on 10-game winner Clay Buchholz.

The club has diagnosed Buchholz with a left hamstring strain, an injury that happened when he was running the bases. Because the Red Sox were off on Monday and have another off-day on Thursday, they don't need a five-man rotation this week, and will give Buchholz some time to heal. The club said he won't pitch during the five-game homestand against the Rays and Orioles, but added that the righty won't be placed on the disabled list.

Patterson activated; Castro sent down

BOSTON -- Eric Patterson, the infielder/outfielder the Sox acquired over the weekend, was activated on Monday and will be in uniform for Tuesday's game against the Rays.

Patterson is expected to help fill the void at second base left by Dustin Pedroia, who is out until the early portion of August with a left foot fracture.

To make room for Patterson on the roster, the Red Sox designated lefty reliever Fabio Castro for assignment. Castro, who had unspectacular numbers at Triple-A, was called up on Friday because the Red Sox bullpen had become depleted during a three-game series against the Rockies. Castro did not pitch in the three days he was on the roster.

Cuban catcher Ibarra close to signing

BOSTON -- Cuban catcher Adalberto Ibarra, who agreed to terms with the Red Sox in April, took a physical for the club in Boston on Monday, according to agent Edwin Mejia via Twitter. Ibarra had been in the Dominican Republic for the past couple of months, awaiting his visa.

In one of his tweets, Mejia posted a picture of his client standing in front of Fenway Park.

Mejia later wrote, "We are extremely excited Ibarra has taken his physical and merely await approval by the Red Sox doctors."

The Red Sox, as a club policy, never confirm a physical with any player until the findings of the physical are complete.

Ibarra is regarded as a promising hitter. Scouts have said he needs more seasoning in the Minors on defense.

Bonser clears waivers, becomes free agent

BOSTON -- The short-lived Boof Bonser era with the Red Sox officially ended on Monday, as the veteran righty cleared outright waivers and declared free agency. Any team in the Majors is eligible to sign Bonser, who is 18-25 lifetime with a 5.19 ERA in 98 games, 60 of which have been starts.

Bonser, who had right labrum and rotator cuff surgery in February 2009 when he was with the Twins, gave up four runs in two innings during his brief stint on Boston's Major League roster.