Gagne was hurt when his right cleat slipped on the mound as he was trying to protect a one-run lead in the bottom of the ninth inning of Sunday's 4-3 victory. The injury is termed as a strain of the right hip and gluteus by the club.
"I'm frustrated," said Gagne, who was shut down and sent for an MRI exam after throwing a dozen light warmup pitches Monday morning. "I don't really feel it walking or laying around. I think I'd be all right in four or five days, but we can't put that kind of strain on the bullpen."
Rangers manager Ron Washington said the decision to deactivate Gagne was also intended to protect the closer from reinjuring his elbow or back, if he was to alter his delivery to compensate for pain in his leg.
"We need him healthy," Washington said of Gagne. "And we need him down the stretch, not just in April. It's tough, because he's your closer. But when you have a team, you move on. We're going to miss him, but somebody else will step up. Those other guys in the bullpen are ready."
Gagne's injury spawned opportunity for Frank Francisco, the hard-throwing right-hander recalled Monday from Triple-A Oklahoma. Francisco had a solid rookie season in 2004 before being sidelined by Tommy John elbow ligament transplant surgery. He pitched only 6 1/3 Minor League innings in 2005 and just 7 1/3 big-league innings for the Rangers last September.
Francisco opened this season at Oklahoma, where he has been lights-out for the RedHawks. He faced 23 batters in five scoreless appearances, working six hitless innings with three walks and 14 strikeouts.
Bullpen adjusts: With Gagne sidelined, Washington said he will restore Akinori Otsuka to his former role as closer, and entrust the eighth-inning setup job to right-hander Joaquin Benoit.
But Francisco, who was a strong setup man in 2004 ahead of former closer Francisco Cordero, could also see some late-inning work if he demonstrates his secondary splitter and slider have improved to complement his 94 mph fastball.
"That fastball he's been blowing guys away with at Triple-A might be foul balls up here, which means his pitch count goes up," Washington said. "They don't care about heaters up here."
But Francisco said he is confident his stuff will allow him to compete at the Major League level.
"I didn't have my best spring," he admitted. "I think I did good, but I could do better. Now my stuff has been good.
"I do what I do. I throw my fastball for strikes, I get ahead in the count. I just get people out."
Wilkerson available: Outfielder Brad Wilkerson, who missed the previous five games with a sore patella tendon in his left knee, was available to play Monday but was not in the starting lineup. Washington said he would probably start Wilkerson in Tuesday afternoon's series finale against Seattle left-hander Jarrod Washburn.
"Lefties don't bother Wilky," Washington said.
Wilkerson is 1-for-3 in his career against Washburn, with one strikeout.
Sunday's Minor Stars: The top three performances from the four Minor League teams on Sunday:
Gold: Center fielder Freddy Guzman was 3-for-3 with a double, triple, two walks, one RBI, one stolen base and three runs scored to lead Oklahoma to a 7-2 victory over Round Rock.
Silver: Double-A Frisco catcher Kevin Richardson was 3-for-5 with a home run, three RBIs and two runs scored in the RoughRiders' 14-11 loss to Corpus Christi.
Bronze: Left-hander John Koronka (1-2) picked up his first win of the season for Oklahoma, giving up two runs on four hits in seven innings of the RedHawks' victory.
He said it: "Momentum seems to last very short around here. So I don't want to talk about momentum." -- Washington, whose team had won two in a row entering Monday's series opener with Seattle
Briefly: Catcher Gerald Laird, who took a hard foul ball off the top of his left kneecap in the eighth inning Sunday, said he was sore but able to start Monday night. ... Chicago White Sox lefty Mark Buerhle, who pitched a no-hitter last Wednesday against the Rangers, was named the American League's Player of the Week. ... Sunday's comeback victory was the Rangers' first when trailing after six and seven innings. Texas entered Monday's game 1-10 when trailing after six innings and 1-9 when behind after seven. ... First baseman Mark Teixeira extended his consecutive-games played streak to 465. Alex Rodriguez holds the club record with 482 consecutive games played.
Up next: Washburn (0-2, 4.42) faces Rangers right-hander Vicente Padilla (0-3, 6.00) in the afternoon finale of this two-game series at Rangers Ballpark in Arlington. First pitch is scheduled for 1:05 p.m. CT.
Ken Daley is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.