The Red Sox played Game No. 53 last night.

Same with Dustin Pedroia.

Given what we now know about what Pedroia has been dealing with since the first game of the season — a complete tear of the ulnar collateral ligament in his left thumb — last night could have been Game No. 2 for Pedroia.

For most players, it would have been and should have been No. 2. A torn UCL in the thumb takes about eight weeks to heal.

Last night marked the beginning of the ninth week of the season.

To Pedroia, the idea of missing April and most of May with an injury he considers nothing more than a flesh wound was repugnant.

So was hearing that his previously unknown injury was going to become public knowledge.

“People shouldn’t know if you’re 100 percent or not. It is what it is, and it’s my responsibility to perform well,’’ Pedroia said before taking his usual spot at second base against the Phillies. “My mindset is if I’m nicked up, I have to find other ways to perform. That’s the way I think about it. Maybe I’m crazy.’’

Pedroia did not make the best baseball decision of his career in the ninth inning of Opening Day on April 1 at Yankee Stadium, where he slid headfirst into first base in the ninth inning with the Red Sox up by six runs. He jammed his thumb on the bag and the next day had an MRI. It revealed more than a nick.

Pedroia said he was told he had a complete tear of the UCL, although it was impossible to say if it was a pre-existing tear or the result of that slide. The soreness and discoloration were real, however. Doctors told Pedroia he could play through the injury if he could withstand the symptoms and that he would not risk doing long-term damage.

The first part of the equation was easy for Pedroia. Once he heard the second part, the decision entered no-brainer territory.

“Yeah, I’m smarter than a lot of people think I am,’’ Pedroia said. “I understood. You go and come back in eight weeks — that’s a lot of ballgames without one of the team’s best players, so my job’s to go out there and do the best job I can to help the team win. That’s the way I look at things.’’

Principal owner John Henry recalled how distraught he was when he heard the news of the complete tear.

“It would have taken the heart and soul out of that club on Opening Day,’’ Henry said. “We already had lost (David Ortiz) and we didn’t know when he was coming back. It just meant so much to that club to have Dustin in the lineup every day.’’

Henry was well aware of the magnitude of the injury news. He knew that as bad as the impact to the team was on so many levels, the long-term health of Pedroia meant more.

He tried to make sure Pedroia understood there was nothing wrong with taking the conservative route in order to allow the thumb time to heal.

“I had two or three talks with him during the time about what he should do. I kept talking about it’s a long season and he kept talking about not missing a game,’’ Henry said. “The guy played through the pain, through the swelling, the discoloration. He played through it, and no one ever knew. And he’s hit what, .330?’’

General manager Ben Cherington mentioned that Pedroia played through a broken finger at the end of last year, so what happened this time around is not necessarily an aberration. Still, he appreciates what it means.

“It’s a great credit to Dustin’s character, his toughness and his commitment that he didn’t want to miss a single inning and was able to do that and ultimately played very well,’’ Cherington said.

It’s impossible to say if the thumb injury has been behind a slight drop in Pedroia’s power numbers. His slugging percentage heading into last night was at .448, 30 points higher than it was through his first 53 games last year but 12 points below his career average. He had five home runs at this point last season, and he has three now.

He has raised his slugging percentage 60 points since the beginning of the month and has hit two of his three home runs in the past two weeks.

“You could speculate that’s why his power is down, or that he’s not driving the ball as much. The thumb may not be painful, but there could be some mild instability,’’ said Chris Geary, chief of sports medicine at Tufts.

For a right-handed hitter, left thumb instability is not necessarily the worst spot for such an injury as far as bat grip is concerned. Still, the possibility exists that Pedroia will need the ligament to be corrected via surgery after the season ends.

Pedroia had as much interest in elaborating about how his injury has affected his swing or the possibility of offseason surgery as he did in letting this story get out.

“It’s a player’s decision to shut it down or play,’’ Pedroia said. “Players play.’’

And Pedroia’s a player.

An everyday player.