Did Sabathia pitch too long Monday?

“One game at a time.” It is a mantra of baseball managers, an approach that enables them to focus on the one thing that they can control — the game in front of them — without worrying about other concerns.

“One game at a time.” The Yankees’ Joe Girardi — in a decision that was curious at best, dangerous at worst — used precisely that rationale for extending left-hander CC Sabathia to eight innings in a blowout of the Red Sox on Monday night.

In this case, “one game at a time” did not apply.

Not when the Yankees might need Sabathia on short rest in a one-game, wild-card playoff Friday. Not when Sabathia has been on the disabled list twice this season. Not when the Yankees will need him to fill his usual role of workhorse in the playoffs, should they advance.

Another baseball mantra would have been more appropriate on Monday night — a pitcher has only so many bullets. Sabathia threw 103 pitches in the Yankees’ 10-2 victory, 103 pitches on a night when the score was 9-0 after two innings. Girardi easily could have lifted him after five innings and 70 pitches, or shortly thereafter.

Nitpicking? Perhaps. The Yankees, thanks to the Orioles’ 5-3 loss at Tampa Bay, took a one-game lead in the AL East with two to play. If they win the division, Sabathia will pitch Game 1 of the Division Series on at least normal rest, and possibly with an extra day.

Of course, Girardi was not sure the Orioles would lose while his game was in progress. And while his bullpen worked 91 innings in September — by far its highest monthly total of the season, according to STATS LLC — the Yankees should have had enough bodies with an expanded roster to preserve an eight-run lead against the depleted Red Sox (the Yankees led 9-1 going into the seventh).

Girardi, though, reasoned otherwise, specifically saying that he wanted to stay away from right-hander David Robertson. The manager’s immediate concern was the next game Tuesday night, when right-hander David Phelps will replace righty Ivan Nova in the rotation, making only his second start since Sept. 12. Thanks to Sabathia, the Yankees’ bullpen will be rested — righty Freddy Garcia covered the only other inning the team needed.

“I’m not worried about Friday,” Girardi said, referring to the potential wild-card game. “I’m worried about today. And now that today is over, I’m worried about tomorrow.

“You start thinking too far ahead, you put yourself in a bad position. With (Phelps) going tomorrow, I want a full bullpen. And I think that’s important.”

Fair enough, though some in the media wondered if Sabathia wanted to stay in the game so that he could reach 200 innings for the sixth straight season (he hit that number exactly) and reach 200 strikeouts (he fell three short).

Both the pitcher and Girardi denied that such goals influenced the decision, and that had better be the case. The pursuits of an individual should never override the priorities of a team, particularly at this time of year.

The good news is Sabathia again looks like the CC of old, giving the Yankees renewed hope that they can make a lengthy postseason run.

Sabathia, since returning from left elbow soreness on Aug. 24, has a 2.93 ERA in eight starts. He has thrown eight innings in each of his last three, allowing two earned runs or less.

Girardi said — and Sabathia agreed — that the pitcher’s changeup on Monday night was the best it has been all season.

“He threw it whenever he wanted, anytime — for strikes, and for strikeouts,” Red Sox right fielder Cody Ross said.

Red Sox third baseman Danny Valencia concurred, saying the team was surprised that Sabathia did not attack with his fastball the way he normally does, using more off-speed stuff.

Sabathia, for all of his physical issues this season, evidently is doing something right — he increased his American League lead in strikeout-to-walk ratio on Monday night, striking out seven and issuing only one walk.

He always has been one of the game’s most accountable players, accepting blame for defeats, insisting upon taking the ball. But at 32, he has worked more than 2,600 innings, including postseason. At times, he needs to be protected from himself.

Here are snippets of his postgame media session Monday night:

Could he pitch on short rest in the wild-card game?

“Of course. Yeah.”

Will anything change based on what he has endured this season?

“That wouldn’t matter anyway. It’s time to go. It’s time to put up or shut up. I want the ball.”

How soon could he come back?

“Tomorrow. Whenever. I’ll take the ball whenever they need me to.”

Short rest, normal rest, extra rest, whatever the case might be?

“Of course,” Sabathia said. “I don’t think that’ll ever change.”

In the end, he threw only 30 or so extra pitches Monday night, and they were less stressful than they otherwise might have been due to the lopsided score. Still, Girardi could have lifted Sabathia earlier with virtually no risk.

Better the manager should have prepared for all possibilities than proceeded “one game at a time.”