Ross has a small fractured bone in his left foot. The injury occurred when he fouled a ball of his foot in Friday night's game against Philadelphia.
General manager Ben Cherington said Monday that Ross could be sidelined for 6-8 weeks, but manager Bobby Valentine expressed hope Tuesday that Ross could be back sooner.
"At worst case it's not as bad as we thought it was yesterday. At best case it's much better," Valentine said. "At worst case it seems like a couple weeks rather than multiples."
To make room for Podsednik on the 40-man roster, the Red Sox moved pitcher Daisuke Matsuzaka from the 15-day disabled list to the 60-day DL.
Youkilis was placed on the disabled list on May 2, retroactive to April 29, with a strained lower back. He was in the starting lineup at first base for Tuesday night's game against the Baltimore Orioles.
Asked Tuesday afternoon how he felt, Youkilis replied, "Good to go."
Youkilis is batting .219 with two homers and nine RBI in 18 games.
Sweeney hurt his head making a diving catch during Saturday's game against Philadelphia. He failed a major league-mandated concussion test on Monday.
The move is retroactive to Sunday, so Sweeney could return as soon as this Sunday, when Boston hosts Tampa Bay.