Sandy Alderson said Tuesday night he hoped the Mets’ weekend sweep at the hands of the lowly Braves was the low point of the season.

The “nadir,” he called it.

That 10-dollar word was still hanging in the air at Citi Field when Bartolo Colon faced the first batter against the Royals. And a giant “uh-oh” went through the stands when a line drive on the fourth pitch of the evening clipped Colon’s right thumb and forced him from the game.

Fortunately for the Mets, the ball off the bat of Whit Merrifield did not break Colon’s thumb. It only bruised it.

From the ashes of that inauspicious beginning, the Mets bullpen got the next 26 outs almost without incident in a 2-1 victory over the defending World Series champions before 40,122.

“Those are the kinds of games I really believe you should grow from,” manager Terry Collins said. “Everybody who came in the game pitched great. To hang on in that situation, that was a great outing by every guy out of the pen.”

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When Colon got hurt, every member of the Mets bullpen started stretching except for closer Jeurys Familia. Even Matt Harvey volunteered to throw an inning.

“Guys were like, ‘Is it me?’ ” Erik Goeddel said. ‘ “Is it going to be that guy?’ ”

That guy was Hansel Robles, who replaced Colon and lasted 3 2⁄3 innings and 65 pitches — both career highs. Almost unbelievably, Robles was still pitching in the fifth inning with a 2-0 lead forged on home runs by Asdrubal Cabrera in the first and Yoenis Cespedes in the fourth off Ian Kennedy.

Robles (1-3) allowed one run and five hits, walked one and struck out six. A protégé of Colon’s, Robles even looked like his mentor with a couple of mighty swings in his second career at-bat in the third inning. Robles eventually struck out looking, but not before getting his money’s worth.

And the Mets got their money’s worth out of Robles. He left after allowing an RBI single to Brett Eibner to bring the Royals to within a run in the third matchup of the season for last year’s World Series combatants.

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“That’s a tremendous job they did tonight, especially from Robles,” Colon said through a translator. “I know he was definitely caught off guard with having to run out there at the spur of the moment.”

When Robles left, Collins double-switched in Goeddel. Unconventional Royals manager Ned Yost decided to take his best shot even though it was only the fifth when he sent up his designated hitter, Kendrys Morales, to bat for Kennedy (5-6), who had thrown only 73 pitches.

Morales nearly made Yost the toast of Kansas City when he sent a drive to right. But Curtis Granderson caught it at the fence and Goeddel got the next two outs to strand the tying run at third.

Goeddel ended up throwing two shutout innings. Jerry Blevins pitched a 1-2-3 seventh. Addison Reed did the same in the eighth. In the ninth, Familia shook off a two-out single by Cuthbert to notch his 23rd save.

Colon, by the way, started Tuesday night only because the Mets flip-flopped him with Noah Syndergaard, who will face the Royals this afternoon. Collins said the Mets made the move because Syndergaard threw 115 pitches in his last outing. It also lines up Thor to face the Nationals next week.

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Colon said he would know Wednesday if the swelling had gone down enough to allow him to avoid a DL stint. His next start is scheduled for Sunday in Atlanta.

“First thought that popped into my head was, ‘God, please don’t let this be a broken thumb,’ “ Colon said. “I had never been hit there before. I think I just have to wait until tomorrow to see how it’s feeling.”

Asked what his first thought was, Collins said: “There’s kids watching this show tonight. So I can’t tell you my reaction.”