That's when the New York Yankees closer found his classic form again.
Rivera pitched himself in and out of trouble Saturday, escaping a bases-loaded, no-out jam in the ninth inning and preserving a 2-1 victory.
"You can't have doubts," Rivera said. "You have to make pitches. If you have doubts, a lot of things can happen."
After Mike Mussina pitched six shutout innings, Rivera took over in the ninth with a 2-0 lead. The Red Sox quickly scored a run and were poised to get more, but Rivera struck out Coco Crisp, got Jason Varitek on a popup and fanned Julio Lugo for his 23rd save.
"We gave ourselves a great chance with really good at-bats in the ninth and then Mariano went to work and really carved us up for three batters," Boston manager Terry Francona said. "He gave himself no wiggle room and he didn't need it."
The Red Sox were on the brink of capturing the first three of the four-game series and fourth in a row in the season series when Rivera escaped.
"It was a big game for us," Yankees manager Joe Girardi said.
Melky Cabrera and Brett Gardner, two of New York's three healthy outfielders, each drove in a run and made a nice play in the field. Cabrera had an RBI single in the second and Gardner's sacrifice fly made it 2-0 in the sixth.
Justin Masterson (4-3) hit three batters, threw a wild pitch and walked two, but managed to hold the Yankees in check in his six innings. The rookie right-hander allowed six hits in his first appearance against New York.
Dustin Pedroia went 2-for-4 to extend his hitting streak to 13 games for Boston, which almost dealt the Yankees a heartbreaking loss.
"When you get bases loaded and nobody out, most of the time we're still playing," Francona said.
Mussina (11-6) allowed four hits and walked one in his first win over the Red Sox since June 5, 2006. He was 0-3 with a 7.71 ERA in his previous six games against Boston.
Mussina has won 10 of his last 14 starts and his 11 wins are his most before the All-Star break since he went 12-3 in the first half in 2002. His latest effort came in front of Francona, who will manage the AL in the All-Star game at Yankee Stadium on July 15, but Mussina wasn't interested in lobbying on the eve of the rosters announcement.
"There are a lot of guys who deserve to go, a lot more than there are spots in both leagues," he said. "You could make a whole other team."
Jose Veras and Kyle Farnsworth each worked a perfect inning to set up Rivera, who hit two batters in a game for the first time in his career. He also allowed a run in a save situation for the first time this season.
"It definitely was interesting," Rivera said. "You definitely don't want to get into that situation but it happens. You just have to deal with it."
Boston's first four batters reached and Mike Lowell's RBI single cut it to 2-1. Crisp's strikeout was the 900th of Rivera's career, but it was Varitek who was really kicking himself after the game.
"He's Mariano Rivera, but in that situation I've got to do something more," said Varitek, who popped out on a 2-0 pitch.
Red Sox slugger Manny Ramirez was hit three times, tying the major league record, and the teams combined for seven hit batsmen total, matching a modern big league mark, according to the Elias Sports Bureau.
The Yankees, who have scored two runs or fewer in five of their past seven games, took the lead in the second inning. With two outs and Jason Giambi on first, Robinson Cano lined a single into center field and Cabrera grounded Masterson's next pitch into right.
J.D. Drew came up throwing but Giambi got his left hand on the back edge of the plate with a nifty slide past Varitek.
New York loaded the bases in the third but Masterson struck out Giambi and Pedroia made a nice play on Wilson Betemit's grounder to end the inning. Kevin Youkilis also snared Giambi's liner up the first-base line with two outs and a runner on third in the fifth.
Mussina got some help from his defense, too. Gardner threw out Pedroia trying to stretch a first-inning single to left, and Cabrera made a diving catch in center to take a hit away from Lowell with a runner on first and no outs in the fourth.
New York played without outfielder Johnny Damon, who injured his left shoulder trying to haul in Youkilis' triple in Saturday's loss. Damon lost Youkilis' drive when he crashed into the left-field fence, and the ball rested on the fence briefly before rolling back onto the field.
Damon said he felt better and would know more Sunday about whether he can avoid going on the disabled list for the first time in his 14-season major league career.
Francona on picking the team for the All-Star Game: "I think we owe it to the players for it to be agonizing, and it has been." ... Yankees C Jorge Posada got the day off. Girardi said Posada wasn't feeling well, hampered by a cold that's going around the team. ... Girardi said OF Hideki Matsui (left knee) probably will be evaluated on Tuesday. ... Seen in the crowd: Phoenix Suns point guard Steve Nash and talk show host Jerry Springer.