The Rangers, with Scott Feldman on the mound, trailed 4-0 after one inning and 5-3 going into the seventh before rallying for their 11th straight victory.
"Falling behind four early is not easy," Rangers manager Ron Washington said. "But they kept fighting and putting innings together. Tonight they did it."
The Rangers' winning streak is the longest in the Major Leagues this season and the second longest in club history. The longest was a 14-game streak in 1991.
"We were slow coming out of the gate but we just kept after it and kept battling," third baseman Michael Young said. "Tonight wasn't a clean game. Feldman had a tough first inning, but he battled and gave us a chance.
"I just like the way we are playing. It has nothing to do with wins. We're working hard and playing hard and our lunch-pail mentality is starting to pay off."
All 11 victories have come against the National League, making this the third longest winning streak in the 14-year history of Interleague Play.
"We're playing really good baseball," second baseman Ian Kinsler said. "Our starters are battling their tails off, everybody is playing extremely well. You can't say enough about bullpen. When we're down in the game, they come in and give us a chance to come back. When we're up, they're putting games away.
"There was no panic with our team at any point in the ballgame. They scored four in the first but we knew we were able to score runs and were able to battle back. There was never a sense of a letdown. We knew if we executed our game plan and played the game hard, we would have a chance to win."
Young and Josh Hamilton helped spark the comeback while achieving personal milestones along the way. Hamilton was 3-for-4 with a pair of doubles and has now hit in 18 straight games. He is 36-for-72 (.500) with eight doubles, eight home runs and 24 RBIs during the streak.
"The man is swinging the bat, that's all you can say," Washington said.
Hamilton helped the Rangers pull to within two runs. Young helped close the gap in the seventh with a record-breaking triple.
After Elvis Andrus led off with a single and stole second, Young hit a high fly down the right-field line off of Pirates reliever Evan Meek. Right fielder Lastings Milledge raced over and tried to make a diving catch but missed.
The ball fell and Young raced to third with an RBI triple. That was the 45th triple of his career, allowing him to pass Ruben Sierra for the most in Rangers history.
"It's pretty cool," Young said. "I played with Ruben Sierra. It means a lot, especially in tonight's game. It was kind of a momentum shifter. I was just trying to get Elvis over and caught a break."
Kinsler followed with a single that brought home Young with tying run. Meek had allowed just three earned runs over 41 innings and 34 appearances before the Rangers scored two off him in the seventh.
"When a team is hot like Texas, a guy that doesn't give up runs gives up two runs," Pittsburgh manager John Russell said. "As we've seen all year, 19 out of 20 times he's going to come in and shut it down. They are a really hot team right now."
Feldman went six-plus innings, allowing five runs. Then the bullpen took over as Darren Oliver pitched two scoreless innings and Frank Francisco pitched one. That allowed the Rangers a chance to win it in the ninth.
"You can't say enough about the job our bullpen has done," Kinsler said.
Andrus led off the ninth with a walk off of Pirates reliever Steven Jackson and went to second on Young's single. Kinsler flied out to center, but Guerrero ripped a single to left and the found himself swarmed over by teammates at first base.
The winning streak is 11 and counting, and there was only Oliver to sum it up.
"Ride the wave, dude," Oliver said. "Ride the wave as long as you can."