Ponson delivered a much-needed strong outing in his return to Texas, Jason Giambi homered, and Mariano Rivera showed no signs of an aching back in saving New York's 5-3 win over the Rangers on Wednesday night.
The Yankees snapped a two-game skid and stopped their slide in the hunt for the AL wild card, a race in which the Rangers have become a looming contender.
New York is 3 1/2 games behind Boston in the AL wild-card race, and Texas is 2 1/2 back of the Yankees.
For Ponson (7-2), released by Texas in June, there was little extra satisfaction in beating his former team.
"I think everybody in this clubhouse wants to go to the playoffs," said Ponson, who gave up three hits in 6 1/3 innings. "It doesn't matter who we win against."
The reliable pitching came on the same day the Yankees put Chamberlain, their 22-year-old right hander, on the 15-day disabled list with rotator cuff tendinitis in his right shoulder.
The Yankees said Chamberlain will rest for about a week before starting a throwing program, something New York manager Joe Girardi admitted he didn't "know exactly what it means."
Still, he was encouraged by the diagnosis.
"We're not going to rush anything," Girardi said, "but that's a pretty good diagnosis."
Rivera, who hadn't pitched since Friday because of back spasms, threw a one-hit ninth for his career-best 27th consecutive save this season. The Yankees had given up 26 runs in their previous three games, and Girardi had been expressing concern about his pitching staff.
Derek Jeter had two hits and two RBIs after attending a memorial service earlier in the day in Oklahoma City for former Yankees star and longtime broadcaster Bobby Murcer.
It was just the fourth victory in 11 games for the Yankees, who avoided dropping four straight on the road for the first time this season.
New York catcher Ivan Rodriguez, acquired last week from Detroit, left with a bruised right knee in the second inning after Rangers outfielder David Murphy plowed into him at home plate. Rodriguez was not seriously injured and was listed as day-to-day.
"You just block and wait for impact," Rodriguez said. "I've been hit harder, but he hit me pretty good on my knee. I never got hit in my knee like that at the plate."
The news wasn't as good for Murphy. The standout rookie -- who leads AL rookies in RBIs, hits and doubles -- is expected to miss two-to-four weeks and will have an MRI taken on his right knee Thursday.
The Rangers said Murphy strained a knee ligament.
"We banged each other up pretty good," Murphy said. "The replay didn't look as bad as it feels."
Michael Young homered for the Rangers, who had won three straight.
With Chamberlain's timeline unknown, and Chien-Ming Wang and right-hander Phil Hughes still out, the Yankees were glad to get a solid outing from Ponson, who earned his third win since joining the club.
Ponson loaded the bases with no outs in the second inning before Chris Davis' single gave Texas a 2-0 lead.
The Yankees tacked on two more in the third off starter Tommy Hunter (0-1), who was sloppy in his second career start. The right-hander gave up five runs and eight hits in 4 1-3 innings.
The Rangers, who beat the Yankees on Monday with a grand slam in the bottom of the ninth, had no such drama with Rivera on the mound. He struck out two and got his first save since July 25,
"The last thing on my mind was my back," Rivera said. "I was just trying to get people out."
With Chamberlain on the DL, the Yankees are expected to call up Ian Kennedy from the minors to start Friday. Dan Giese will start Saturday. ... Yankees DH-LF Hideki Matsui hit 37 pitches during batting practice at the club's facility in Tampa, Fla. Out since June 22 with a left knee injury, Matsui is expected to begin a running program Thursday. ... RHP Kevin Millwood, who began the season as Texas' No. 1 starter, had a bullpen session and will make a rehab start for Double-A Frisco on Saturday. Millwood has been on the DL since July 26 due to a right groin strain. ... Texas DH Milton Bradley missed his eighth straight start due to a strained left quadriceps but was available to pinch hit. Rangers manager Ron Washington said Bradley could be ready to return to the lineup this weekend at Baltimore.