To fill Matsui's place on the 25-man roster, the Yankees recalled outfielder Kevin Thompson from Triple-A Scranton/Wilkes-Barre. Thompson batted .300 in 19 games for the Yankees last season across three stints, and is expected to assume Melky Cabrera's role as a reserve when he meets the team in Minnesota on Monday.
Manager Joe Torre had been optimistic in his earliest assessment of Matsui's condition, saying that the outfielder could perhaps rejoin the club within three to five days.
But an MRI exam performed on Sunday showed some blood, indicating a strain, and Torre said that the move to the disabled list was triggered in Matsui's interests.
"He certainly understood," Torre said. "I think the biggest thing is that you protect the player against himself at this point in time."
General manager Brian Cashman said that the club's history with strained hamstrings has generally spelled at least a two-week recovery period. He cited the case of second baseman Robinson Cano, who missed 35 games last season after straining his left hamstring in a late-June game.
"It's something we just don't want to play with," Cashman said. "It's something that we could have held back for five or six days, but with hamstrings, it's just not worth the gamble.
"We're going to take the safe route and make sure that this is not an issue that carries us deeper into the season, so we want to get it out of the way. As hard as it is to put a guy like Hideki Matsui on the DL, it's the right thing."
Matsui believes that the assignment will offer him more than enough time to recuperate and rejoin the lineup. He said that he did not attempt to dissuade Cashman or Torre from the move.
"It's a fact that I will not be able to play a couple of games," Matsui said. "That would mean that by not being on the DL, I wouldn't be a factor to the team, and I'm actually inconveniencing the team in that process."
He suggested that the chilly conditions in the Northeast -- Saturday's first pitch was thrown with a recorded 39 degrees -- may have contributed to the injury, but added that his preparation for the season may have not been adequate.
"From my perspective, I gave it my best," he said. "The fact that this happened means somewhere, something wasn't right."