Then came Friday night, when Papelbon turned out to be very human, giving up three hits and two runs in one inning and blowing the save in a game against the Yankees that the Red Sox led, 7-2, before losing, 8-7.
So what happened?
"It was a bad, bad night for me," said Papelbon. "Real bad night for me. Just everything, from top to bottom, it was just a bad night. Nothing felt good. I would chalk that one as probably the worst outing of the year so far. Nothing really went good for me. I wasn't sharp."
And when you aren't sharp against the heavy-hitting Yankees, trouble will inevitably find you.
However, Papelbon is the antithesis of a man who dwells on a bad outing. Perhaps that's what makes him so successful.
"I can't go through the whole season and be perfect," said Papelbon, who has converted 35 of 38 save opportunities. "I can't remember a closer who ever went through a season without blowing a save. If you're a closer that goes through a season and doesn't blow a save, I'd like to meet you."
Papelbon was looking forward to getting the ball again on Saturday, if necessary.
"We've got a new game today," said Papelbon. "That's the great thing about baseball. You get to play 162 games, so ... [yesterday] is gone. Today is a new day. We win today, we're right back at even [in the series]. We win tomorrow, we're ahead. It's another game. We're still in first place, last time I checked."
Okajima's slide continues: Left-hander Hideki Okajima was nothing short of brilliant for most of the season, but he's stumbled badly of late. Okajima has been scored on in three of his last seven outings. Friday night was Okajima's worst game of the season, as he was knocked around for three hits and four runs in one-third of an inning. From Aug. 8 through Saturday, Okajima's ERA went from 0.98 to 2.28.
While fatigue has been mentioned a lot as a possible reason for Okajima's decline, Red Sox manager Terry Francona thinks that familiarity -- particularly when it comes to teams like the Yankees -- is a bigger factor.
"I think early on, when somebody is new, you definitely have an advantage, especially when you have an offspeed pitch that people haven't seen," Francona said. "Then, I think you have to prove yourself when you go through the second time that you're pretty good, which I think he did. Now, you play people in your division 19 times, and Oki has pitched a lot of those games. He's got seven or eight experiences against those guys, and he's got one year in the league. I thought last night, he left balls over the middle of the plate. He doesn't do that normally. He threw the ball down the middle and he paid for it."
Coco good to go: Center fielder Coco Crisp, a last-minute scratch on Friday with stiffness in his left hip, was back in the lineup on Saturday. In fact, Crisp got enough treatment on the hip during Friday's game.
"I think he'll be OK," Francona said on Saturday. "If he's not, we'll get him out of there. He had actually worked himself to the point last night where he made himself available. Hopefully, that's the case today."
Hinske gets call in left: It was Eric Hinske, not Jacoby Ellsbury, who started Saturday's game in left field. Hinske came into the game as a .455 lifetime hitter (10-for-22) against Yankees starter Chien-Ming Wang.
"Wang has been so good against so many hitters, and Hinske has taken some really good swings," said Francona. "Maybe he takes a couple of at-bats and lines one into the gap or something, and then we put Ellsbury in to run for him or something like that."
Saturday was the 17th game in a row that Manny Ramirez -- out with a strained left oblique -- was out of the lineup.
Coming up: In a marquee pitching matchup featuring two of the best of this generation, Curt Schilling (8-7, 3.93 ERA) will take on Roger Clemens (6-6, 4.45 ERA) in Sunday night's finale of this three-game series. First pitch is scheduled for 8:05 p.m. ET.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.