Source: Varitek (foot) out 4-6 weeks

BOSTON -- Red Sox catcher Jason Varitek, who was supposed to assume everyday catching duties with Victor Martinez on the disabled list with a fractured left thumb, instead is joining Martinez on the disabled list with a fractured foot, a major league source confirmed Thursday night.

WBZ-Channel 4 in Boston was the first to report that Varitek sustained a leg injury and showed footage of Varitek's charity miniature golf event Thursday night, in which the Sox captain could clearly be seen limping.

Details were sketchy, but a major league source said that while Varitek is expected to miss four to six weeks, it could be less. It is not certain which foot was fractured, but a source said Varitek did not break the foot in Tuesday night's near-collision with third baseman Adrian Beltre.

Varitek was seen returning to the dugout in the middle of the fourth inning Tuesday night in some obvious discomfort, but when asked about it afterward, Varitek said: "Next [question]."

Varitek caught Wednesday night's game against Tampa Bay and after the game, Varitek was observed limping badly out of the Red Sox clubhouse.

Martinez went on the DL after being hurt Sunday in San Francisco, and the Red Sox promoted catcher Gustavo Molina from Pawtucket. Thursday night, the Red Sox brought catcher Kevin Cash back into the fold, acquiring him from the Houston Astros for infielder Angel Sanchez.

Cash, who was designated for assignment by the Astros on June 22, then outrighted to Triple-A Round Rock, appeared to be a move just adding depth to the catching corps, with two catchers in Pawtucket, Dusty Brown (thumb) and Mark Wagner (hand) on the DL. But with Varitek down, the Red Sox targeted Cash to fill in on the big-league level, where he is expected to share catching duties with Molina.

Cash was with the Red Sox in 2007 and '08, and distinguished himself by his work with knuckleballer Tim Wakefield.

"I'm excited, very excited," Cash said from his hotel room in Memphis about returning to Boston. "My time there was probably the most memorable time I have ever had in baseball. It was a lot of fun."

The shocking news about Varitek -- club officials were not responding to requests for comment late Thursday night -- continued a week of casualties for the Sox. Pitcher Manny Delcarmen (strained forearm) was told on Thursday he will be going on the DL, and with Varitek, that makes five regulars lost by the club in the span of a week.

Dustin Pedroia fouled a ball off his left foot, fracturing it, Friday night in San Francisco, and is expected to miss four to six weeks.

On Saturday, pitcher Clay Buchholz hyperextended his left knee and strained his lower hamstring; the Sox are hoping to avoid placing Buchholz on the DL and that he will miss just one start.

Sunday, Martinez took two foul tips off his left thumb and fractured the tip of the thumb. He went on the DL and has been fitted with a splint, and the Red Sox are hopeful that he will be able to return to action soon after the 15-day period ends. A club source said Thursday night that the plan for now is just to add Cash, with the expectation that another transaction will not be needed if Martinez comes back soon.

And just before this week-long run of injuries, the Red Sox placed third baseman Mike Lowell on the DL because of ongoing problems with his hip.

Outfielder Jacoby Ellsbury has missed all but nine games this season with fractured ribs, pitcher Josh Beckett has been on the disabled list for six weeks with back stiffness, and outfielder Jeremy Hermida has missed the past three weeks with fractured ribs.

Gordon Edes is ESPNBoston.com's Red Sox reporter. He has covered the Red Sox for 12 years and has reported on baseball for 25 years. Ask a question for his next mailbag here.