ST. PETERSBURG, Fla. — Tampa Bay closer Troy Percival was placed on the 15-day disabled list with a left hamstring strain, and the Rays filled the roster opening by activating infielder Willy Aybar today.

Percival, 1-0 with 14 saves in 16 chances and a 2.95 ERA, limped off the mound during the ninth inning of yesterday's 5-3 victory over the Texas Rangers. An MRI exam revealed no significant damage, however the AL East leaders don't want to take any unnecessary chances with the 38-year-old right-hander.

"The good news is it's nothing significant. That's what we were worried about, first and foremost," Rays vice president of baseball operations Andrew Friedman said before the Rays opened a four-game series against the AL Central-leading Chicago White Sox.

"It's never ideal for your closer to go on the DL," Friedman added, "but I do feel confident that we have guys who will step up and help mitigate the loss."

Percival has been a big part of Tampa Bay's success, providing veteran leadership to a young club on and off the field since signing as a free agent in November. A four-time All-Star, he has 338 career saves, 10th on the career list.

Aybar, who's hitting .292 with one homer and two RBIs in 24 at-bats, had been on the DL since April 10 with a left hamstring strain.