Sizemore's assignment to the DL is retroactive to Wednesday, meaning he will be eligible for activation on May 26. That happens to be a scheduled off-day for Cleveland, so the center fielder could potentially be ready to rejoin the lineup for the Tribe's May 27-29 road series against Tampa Bay.
Indians trainer Lonnie Soloff said Sizemore will perform light baseball activities over the next five days before increasing the intensity.
"He's still uncomfortable with lateral movement and more dynamic, unpredictable movements," Soloff said.
The Indians are hopeful that Sizemore will be ready to play as soon as he's eligible to come off the disabled list.
"We're optimistic," Soloff said, adding that he would not expect Sizemore to require a rehab assignment.
Sizemore, 28, initially injured the knee while sliding into second base during the sixth inning of Tuesday's game against the Rays. He remained in the game and indicated later that the knee felt worse as the night wore on. An MRI exam on Wednesday morning revealed no structural damage.
The Indians described Sizemore's ailment as a right knee contusion and he was considered day-to-day. Fortunate for both Sizemore and the ballclub is the fact that the current issue does not involve his left knee, which required season-ending microfracture surgery last June.
Sizemore was limited to 33 games a year ago due to that left knee injury and did not return from the disabled list until April 17 this season. In 18 games for Cleveland this year, Sizemore has looked like his old self again, hitting .282 with six home runs, 10 doubles, 11 RBIs and 15 runs scored.
Over the past five days -- Cleveland's games against Seattle on Saturday and Sunday were both postponed due to rain -- Sizemore steadily increased his activities to test the knee but when he continued to report some discomfort, the Indians elected to shelve him for the time being.
The 27-year-old Buck began the season on the Indians' Opening Day roster but was sent to Triple-A to clear room for Sizemore's return in mid-April. Buck hit .241 with two RBIs in 10 games for Cleveland. He was batting .333 with three homers and 21 RBIs in 18 games for Columbus.
Manager Manny Acta is looking forward to Sizemore's special brand of aggressiveness when he returns from the knee contusion.
"That's what everybody wants guys to be like ... to play hard and go hard every day," Acta said. "Once he comes back, he's going to be fine."