Percival was seen by Dr. Keith Meister, the Rangers orthopedic, on Friday and the Rays are now waiting for Meister and Koco Eaton, the Rays' orthopedic team physician, to confer on Percival's situation.
"He's got some cartilage involvement, it's not a tear," said Andrew Friedman, Rays executive vice president of baseball operations. "I'm still waiting for Koco and Dr. Meister to connect."
Friedman said the films of Percival's knee are fairly clear, leaving them to consider two courses of action. One is non-surgical and involves rehabbing; the other is surgery. In either case, the prognosis for recovery is two to four weeks.
Rays manager Joe Maddon said he will not name a closer during Percival's absence. But Dan Wheeler, Grant Balfour, Chad Bradford and J.P. Howell could all be used in that role.
Percival, 39, heads to the disabled list for the third time this season after injuring his knee in the ninth inning of Thursday's 7-6 Rays win over the Athletics. The closer is 2-0 with 27 saves and a 3.69 ERA this year. He has held opponents to a .162 average, which ranks sixth lowest among Major League relievers. His 351 career saves rank seventh on the all-time list. The Rays are 32-0 in games when he enters in a save situation.
"All of the major things are fine," said Percival of his knee. "It just happened on the cartilage right where it's weight bearing. So they just have to decide whether they can shut it up, medicate it or whether they need to go in [with arthroscopic]. ... I don't know what they are going to do."
Friedman surmised they need to get a "better understanding of the most prudent way to go."
"I don't know yet," Friedman said. "We'll probably have that conversation, let those [the two doctors] connect, let him rehab over the weekend, and Monday have him see Koco. Again, I'm still waiting to talk to Dr. Meister and Koco."
Salas, 29, joins the Rays for the first time this season. He was 4-5 with one save and a 2.62 ERA for Durham in 28 relief appearances. Salas missed all of Spring Training due to visa issues in his native Dominican Republic, and on May 17, was optioned to Durham. Last season, he went 1-1 with a 3.72 ERA over 34 outings as a rookie for the Rays.
Bill Chastain is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.