The scene now shifts back to Anaheim for a decisive Game 5 on Monday night, with Angels right-hander Bartolo Colon facing Yankees right-hander Mike Mussina, a rematch of Game 1, which was won by the Yankees.
Yankees reliever Al Leiter (1-0) faced one batter in the seventh, getting Darin Erstad to bounce into a double play to end the inning and pick up the win. Mariano Rivera tossed two scoreless innings for his 34th postseason save, his first two-inning save in the playoffs since Game 5 of the 2003 ALCS in Boston.
"It doesn't matter how they did; they did it," said Shields, who took the loss. "I didn't get the job done."
Also hitting a snag was the Angels defense, solid all season with Chone Figgins also having contributed two sparkling defensive plays in this series. But it was Figgins who was on the wrong end of a costly misplay on Sunday.
With one out and runners on the corners in the bottom of the seventh inning in a 2-2 game, Derek Jeter hit a ponderous ground ball toward third. Playing at a depth where he could try to turn two or come home depending on how sharply the ball was hit, third baseman Figgins fielded the ball and elected to come home.
Given a week's worth of rain that dumped all day Saturday, postponing Game 4 by a day, the ball was wet and Jorge Posada was running hard. Figgins rushed the throw and the result was low and wide to the inside of the plate.
Bengie Molina's tag was a shade late and the Yankees took a lead their bullpen would not surrender.
"I got off the best throw I could," Figgins said. "It was a slow chopper and the grass was wet. It was bang-bang, a do-or-die play."
Molina said he thought he felt Posada's spikes on his leg and argued the call with home-plate umpire Alfonso Marquez, but after seeing the replay he admitted that Posada was safe.
"If the throw is right on line, we get him out, but that is part of the game," Molina said. "It can happen to anybody."
Figgins, who started at six positions this season for the Angels, has played a solid third base all season, but the pressure got to him momentarily.
"The ball was chopped high," manager Mike Scioscia said. "I think Figgy had a little more time than he thought."
But the game hinged on a crew that had delivered a number of clutch moments during the season and one that had seemingly given the Angels a distinct advantage.
The Yankees had the better closer in Rivera, but the Angels' 'pen was deeper with Shields in concert with newly crowned setup man Kelvim Escobar and closer Francisco Rodriguez.
They had also been given an extra day of rest after rain washed out Saturday's game. So the decision to pull John Lackey with two out in the sixth following Gary Sheffield's RBI single that halved the Angels lead at 2-1 appeared to be a no-brainer.
Lackey was pitching on three days' rest after being called on to sub in for Jarrod Washburn, who came down with a 102-degree fever late Saturday afternoon and a throat infection.
The big right-hander was game, tossing four no-hit innings before Posada doubled in the fifth and allowing just two runs over 5 2/3 innings on four hits.
Shields (1-1) got the out he needed in the sixth, but Robinson Cano opened the seventh inning with an infield single. Bernie Williams lifted a pop fly to center for the first out, but Shields walked Posada.
Ruben Sierra then pinch-hit for center fielder Bubba Crosby and lined a game-tying RBI single to right, which set up Jeter's go-ahead and eventual winning hit.
It was the first runs allowed in 4 1/3 innings in the series by Shields, who has appeared in all four games.
"It was the walk that killed me," said Shields, who added he did not feel tired and will be ready to pitch Monday. "You can't do that in that situation."
Lackey was disappointed that he wasn't allowed to pitch to one more batter, if not another inning.
"I'm not going to take anything away from Scotty; he's had a great year," Lackey said. "But you want to be the guy to make the pitches with the game on the line and I felt I still had the pitches to get the job done."
Lackey had thrown 78 pitches and Scioscia felt his starter may have had about 10 more, but his confidence in his bullpen was the overriding factor.
"John is never happy to come out of the game," Scioscia said. "Sometimes he makes 115 pitches and is not happy. That is part of his makeup. We just needed Shields to have some wiggle room and not have him come into the game in a two-on situation."
The Angels broke a scoreless tie in the top of the sixth, when Juan Rivera led off the inning with a four-pitch walk, went to second on a sacrifice by Steve Finley and scored on Figgins' double down the right-field line. Orlando Cabrera then lined an RBI double to right-center off Yankees starter Shawn Chacon and the Angels led, 2-0.
Chacon was sharp through his first five innings. The right-hander dispatched the first nine batters. Figgins disrupted the perfect game when his sinking liner to left was bobbled by Hideki Matsui for an error. Figgins was then caught stealing.
Vladimir Guerrero was the first Angel to record a hit when he bounced a ground ball that second baseman Cano went hard to his left to make a play on, but the throw was late. Chacon allowed two runs on four hits and a walk with five strikeouts but did not figure into the decision.
All of which set up a one-game playoff.
"I'm never surprised," Erstad said. "You never know what you're going to get on a given day. The bullpen has pitched well this season; they just didn't get it done today."