BALTIMORE -- Chris Sale knew he was approaching a magical milestone, but it wasn't until he heard the roars from the large contingent of Red Sox fans at Camden Yards and received an equally-warm reception from teammates upon his return to the dugout that he knew he got it.

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Strikeout No. 300 in Sale's first season with Boston came on a wipeout slider that froze Ryan Flaherty to end the eighth inning. It was Sale's 111th and final pitch of the night, and it led the Red Sox to a 9-0 victory over the Orioles on Wednesday night. Hours later, Boston clinched a postseason spot due to the Angels' 6-5 loss to the Indians.

On the strength of the 13-K, no-walk performance, Sale became the first AL pitcher since Hall of Famer Pedro Martinez in 1999 to reach 300 K's in a season. Sale also joined Martinez as the only pitchers in the long and storied history of the Red Sox to achieve that number.

"That's special. We all know that's about as good a company as you can get," said Sale. "Just appreciative of it. It's fun. Being here and having that name thrown around is special to me; I don't take it lightly. He's one of the best to ever step on that mound. To be in the same sentence as him is pretty crazy to me."

It was the first 300-K season in the big leagues since Dodgers ace Clayton Kershaw did it in 2015.

To put into perspective how rare a 300-K season is in the offensive-minded AL, consider that Sale joined Randy Johnson (1993) as just the second AL lefty to achieve it since the designated hitter was instituted in 1973. The only other AL pitchers to reach 300 over that same span aside from Sale, Johnson and Martinez? The legendary Nolan Ryan, who did it five times.

It was the 35th time in history an MLB pitcher has notched 300 K's.

"That's history," said Red Sox right fielder Mookie Betts . "Any time you're a part of history, obviously you feel blessed and excited. He's done great. We can't ask for anything more. Just playing behind him has been great."

What the Red Sox are witnessing from Sale in 2017 is something to behold.

Though Sale had slumped a bit in recent weeks, going 2-3 with a 4.64 ERA in the six starts that preceded this one, he displayed emphatically on Wednesday that he still has a lot in the tank. And the Red Sox, who lead the Yankees by three games in the AL East, will need him at his best in October.

"He was dominant, he was powerful for the entire time he was on the mound tonight," said Red Sox manager John Farrell. "Had the game under control, never really had innings where he overworked or labored. He kept his stuff through the entire game. A dominant performance after a year that has been a dominant one. Granted, there's been some hiccups along the way. But tonight he was with complete conviction and maybe the best overall stuff that he's had the entire season."

The Orioles paid the price.

Goodnight after a good night. 🙌 pic.twitter.com/Nh1f5eeZff — Boston Red Sox (@RedSox) September 21, 2017

"If it wasn't for the other team beating you, it's always something to watch, as far as being able to operate at that level," said Orioles manager Buck Showalter. "He's got the changeup that he's real confident in, too. He doesn't miss location much, can go up, go down, breaking balls. You got to cheat so much with the fastball.

"And his angles -- that's what a lot of people miss about pitchers. Some guys are 6-foot-5, 6-foot-6 and don't take advantage of their angles. Some guys are shorter and do. He's got a great angle. It's a release that you don't see. It's tough to simulate and prepare for."

Sale's previous career high for strikeouts was 274 in 2015. In his first season in Boston, he has been a punchout machine.

This was Sale's 18th game this season of 10 strikeouts or more.

Sale's teammates have enjoyed the show, and they made that clear to Sale with the way they embraced him for his latest accomplishment.

"It was fun. I'm appreciative of that," said Sale. "We go through the trenches together and put in a lot of hard work. They don't call these the dog days for nothing. Having them have my back and being able to share that moment with them was special."

The milestone evening happened to occur with Sale's immediate family cheering him on from the stands. Sale's older son, Rylan, accompanied him to the clubhouse after the game.

"It was cool," Sale said. "It was really fun. My wife, both my boys are here, my mother-in-law. Being able to run out and get a big hug from him and my wife and everybody -- it was special having them here for something like this. [Rylan] was pumped."