After a very loud Friday night series opener in which the Red Sox clubbed four home runs and scored eight, Saturday’s game was a far quieter affair.

The Pittsburgh Pirates actually outhit their guests 9-7, but had little to show for it as the Red Sox won 4-2 to officially take the series.

At first, it looked like the Boston bats were picking up right where they left off. Seven men came to the plate in the top of the first and they took a 2-0 lead off Pirates starter Mitch Keller. Jarren Duran led off with a triple and promptly scored on Wilyer Abreu’s single, and Bobby Dalbec’s force-out drove in Rob Refsnyder for the second run.

But when Triston Casas didn’t report to first base for the bottom of the inning after drawing a walk in the top of the frame, the tone changed. The club later announced that the first baseman had exited with “left rib discomfort,” a concerning update for a team already weighed down by several injuries.

“No, he’s not doing okay,” a concerned-looking Cora told reporters postgame. He explained that Casas felt something in his “rib area” while taking a swing in his at-bat. When the first baseman told his manager that he could play defense for the bottom of the inning, but would need to hit for him after, Cora immediately pulled him from the game. He was still undergoing tests when the game ended.

Pablo Reyes entered the game playing third, and Dalbec moved to first. Their only two baserunners between the second and fifth inning were Abreu and Enmanuel Valdez, who drew a pair of walks, only to be stranded. Overall, the Red Sox drew seven walks, but were 2-for-9 with runners in scoring position and left nine men on base.

Fortunately, they had Kutter Crawford on the mound.

The right-hander came into his fifth start in rare form, having set a franchise record by allowing no more than one run or three hits in any of his first four games. He didn’t sail quite as smoothly on Saturday, but that only made the performance all the more impressive.

“He was excellent,” Cora said. “He had enough towards the end. He had to pitch out of some tough situations. He battled today, and he gave us enough.”

Crawford gave up seven hits and let three Pirates walk the plank, but managed to avoid damage almost entirely, finishing his start charged with one (earned) run. He threw 100 pitches, 68 for strikes.

The bottom of the second was his only 1-2-3 inning, and even then, he worked around a leadoff single by getting Rowdy Tellez to ground into a double play. The Pirates stranded at least one runner in every other frame of Crawford’s outing.

In the bottom of the fifth, the Red Sox starter found himself in more trouble than any of his previous starts this season. After giving up a leadoff single to No. 9 hitter Michael A. Taylor, he allowed a one-out single and walk to load the bases. Clinging to a one-run lead, Crawford channeled Harry Houdini, getting back-to-back swinging strikeouts to escape, leaving behind a full diamond.

“We gave him the chance to go out there and compete,” Cora said. “Probably last year, he’s out of the game, but we trust him and he did an amazing job.”

Joely Rodriguez and Greg Weissert had been warming in the bullpen, but when Masataka Yoshida blasted a two-run homer to extend Boston’s lead to 4-1 in the top of the sixth, Crawford returned to the mound. He struck out Tellez and Jared Triolo before issuing a walk to Oneil Cruz.

But when Cora came out to the mound, it wasn’t to collect his starter, as Crawford initially thought. Instead, the manager offered a vote of confidence and returned to the dugout alone. “This is your last hitter. Go get him,” the skipper said he told his starter.

Cruz stole second, but it was for naught as Crawford got Michael A. Taylor to strike out swinging, too.

“It felt good to have Cora kind of leave me out there in that situation and let me work through my own troubles,” Crawford told reporters.

Another six-inning start by the Red Sox rotation. By Apr. 20 last year, the Red Sox rotation had made three starts of at least six innings. Crawford’s performance on Saturday was No. 7, and the rotation’s third such start in the team’s last four games.

“We got to trust these guys to go deep into the game, and I think they have earned the right so far,” Cora said. “We needed him to go deep and he did.’

Crawford’s 0.66 ERA is tied with Roger Clemens in 1991 for third-best mark by a Red Sox pitcher through their first five starts of a season in the Live Ball Era. He’s only given up two extra-base hits this year, and dating back to last Sept. 18, hasn’t allowed a home run in 43 2/3 innings.

“I always trusted him, since Day 1, I saw it. I knew his stuff is really good. When he made the team a few years ago, we made him a reliever,” Cora said. “That was wrong from our end. This guy’s a starter at the big-league level. His weapons, he knows how to pitch, and he’s learning, he’s learning throughout the process, and we’re very proud of him.”

The game was not without some last-minute drama. Chris Martin, Joely Rodriguez, and Greg Weissert combined for two innings, and there was some momentary concern when Rodriguez began the eighth by giving up a leadoff pinch-hit home run to Connor Joe.

Then, with Kenley Jansen on the mound for the bottom of the ninth, Taylor was ruled out on an automatic strike. Furious, Pirates skipper Derek Shelton rushed out to the field and got ejected.

But moments later, Jansen got his third strikeout to clinch the victory and move into sole possession of fifth on MLB’s all-time saves list. After blowing a save in his previous outing, it was an important reset.

“You just gotta have a short memory, you can’t let stuff rattle you,” the veteran closer told NESN’s Jahmai Webster. “I’m still the guy. I’m still the guy, and yeah, I suppose we get older and we gotta work harder for it, and we just gotta keep doing it. Have a short memory, come back out there, and try to be the best.”

The Red Sox are 12-10, but mostly due to their success on the road. They were 3-7 in their first homestand.

“We just gotta keep playing good baseball like this,” Jansen said. “When we get back home in front of our fans, we gotta turn it around and play like we are right now.”

The cherry on top of Saturday’s sundae? The Red Sox defense didn’t make a single error.