Saito, 38, was diagnosed by Dodgers surgeon Dr. Neal ElAttrache, who apparently ruled out surgery for the time being. A sprain means the ligament is either stretched or torn. Saito represents the 15th Dodgers injury requiring placement on the disabled list this season.
"We'll get together with [manager] Joe [Torre] and come up with a plan," general manager Ned Colletti said from the All-Star Game. "Obviously, it is not easy replacing someone like him. As far as trading for a closer, it's a lot like trying to acquire a shortstop -- it's a premium position and most teams don't carry an excess. We also have candidates within the staff. Many times, closers are discovered in times like this. We'll know more about what we'll do short-term in a couple of days. And we'll know more about Saito's status as the rehab develops."
Torre on Sunday said Jonathan Broxton was his closer until further notice. He wasn't sure who would inherit Broxton's setup role, suggesting it would be a matchup decision, although one name he mentioned was Hong-Chih Kuo, even though Kuo's history of elbow operations -- four -- has made him ineligible for repeated short use to this point.
Torre said Kuo could pitch the seventh and eighth innings the way Mariano Rivera did for Torre before becoming the Yankees closer. He also said Joe Beimel "has the courage to do it," although Torre this year has used Beimel more as a true situational left-hander than as a multiple-innings reliever as Grady Little did.
The Dodgers are considering returning Chan Ho Park to the bullpen and calling up Clayton Kershaw to replace Park in the starting rotation for the second half. Torre said Kuo and Park are two of the biggest surprises of the first half, along with third baseman Blake DeWitt.
Broxton, with a fastball approaching 100 mph, has been the closer-in-training going on three seasons. He is 2-2 with a 3.40 ERA, with 46 strikeouts in 39 2/3 innings. He has let five leads get away, although he hasn't actually been in a ninth-inning save situation this year.
But he was last year, when Saito was shelved for a week with a strained hamstring. Broxton converted his first save opportunity, then let a four-run lead get away in a crushing loss in San Diego before Saito returned. Broxton has five career saves and 15 blown saves.
"When I'm in that [closer] situation, I'll approach it the same as last year," said Broxton. "I just look at it like it's the eighth inning. I come out and get outs. It's no different for me."
Broxton said he feels he's ready for the role.
"Hopefully, one day, I will be," he said. "That's been my goal when I started in the bullpen. One day I can do that. Right now, as long as I'm pitching and we're winning, I'll do anything."
Saito, an All-Star last year, was injured while pitching in Saturday's extra-inning loss to the Marlins. He said he warmed up in the bullpen on Saturday night, and felt nothing unusual during strikeouts of Cody Ross and John Baker of the Marlins during the game.
Saito threw four pitches to the next batter, Wes Helms. After the second and fourth pitches, both 94-mph fastballs, he shook his arm and looked into the Dodgers dugout. He left the game with a 2-2 count on Helms, saying he experienced tightness that increased with each pitch.
"It wasn't a stinging pain, but a strong tightness that got worse and worse. It was a good idea to quit," Saito said Saturday night, adding that the discomfort was different than what led to 1997 surgery for bone chips in the same elbow while he pitched in Japan.
Saito was 3-3 with a 2.18 ERA in 39 appearances, and had 53 strikeouts in 40 1/3 innings with 17 saves in 20 opportunities. He was pitching on Saturday night after a night off Friday night, but threw two innings on Thursday night for only the second time this year after pitching one inning Wednesday night.
Ken Gurnick is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.