ST. LOUIS -- After John Jaso's fly ball cleared the center-field fence Friday night, there was a sense of excitement and relief in the Pirates' dugout. Felipe Rivero had just defused a jam in the eighth inning, and thanks to Jaso's home run, he would have a lead in the ninth.
"I was like, 'Yeah, we got it now,'" Rivero said. "Shut the door. Let's go home."
Rivero returned to the mound and finished off another five-out performance to seal the Pirates' 4-3 win over the Cardinals at Busch Stadium. Since taking over as Pittsburgh's highest-leverage reliever, Rivero has recorded more than three outs in four of his seven appearances -- three saves and Friday's win.
"You don't prepare for that. You've just got to be ready every time," Rivero said. "Whatever's going to happen in the game, I'm ready at any point."
Rivero needed only 20 pitches to record five outs and drop his ERA to 0.68, the second-lowest mark among Major League relievers behind Pat Neshek's 0.61.
When the Cardinals tied the game in the seventh, Rivero said, he began getting into "game mode." He watched manager Clint Hurdle call upon right-hander Juan Nicasio to finish the inning and start the eighth.
The flexibility of Nicasio and Rivero, including their ability to come back after completing an inning, is one reason the Pirates placed them at the back end of the bullpen following the demotion of former closer Tony Watson.
"It's not the way we draw it up, but they have the ability to do it, and they're willing to do it," Hurdle said. "They know the team needs them to do it."
Nicasio issued a one-out walk and gave up a ground-ball single to Jose Martinez, putting runners on the corners with one out. In came Rivero. If he felt any pressure with the game on the line in a precarious situation, he didn't show it.
"Relax and take it easy," Rivero said.
But Rivero's "easy" is a heavy dose of high-octane heat. Aledmys Diaz lined out softly to third baseman David Freese on a 101.9-mph fastball, and Paul DeJong flied out to right field on a 101.8-mph pitch. Rivero, who has stranded 16 of his 18 inherited runners this season, cleaned up the mess.

"He hides the ball well, too, so it's going to be a tough ask, whether guys are going up there swinging or bunting," Cardinals manager Mike Matheny said. "He's got good stuff. There's no question about it."
With Rivero back in the dugout, Jaso, who entered the game at first base during the double-switch that put Rivero on the mound, launched his fifth homer off Cardinals closer Seunghwan Oh. For the Pirates, the game was all but over.
"I think he's a guy that opposing teams know is sitting out in the bullpen, waiting. That's what you need as a closer," Freese said. "I know as a hitter, you're kind of looking at the innings and the lineup, this and that, and you understand a guy like that's out there and waiting, it's a scary thing. Fortunately, he's on our club."
After a leadoff walk, Rivero struck out Chad Huffman on a 90.4-mph changeup, induced a popout and got Tommy Pham to whiff on a 100.4 mph fastball. Just like that, Rivero shut the door -- as promised -- on a series-opening win.
"Sick," starter Jameson Taillon said. "When he's hitting spots, he's unhittable. When he misses spots, he gets away with stuff because he's so nasty. … Everything was disgusting."