ST. LOUIS -- The friendship between Adam Wainwright and Yadier Molina has enough depth that they don’t mind embracing in front of millions. It has enough frivolity that occasionally they shoot each other with water-pellet guns. And it possesses enough authenticity that they can call one another out during subpar performances.

Why, just last weekend, it was Molina who yelled to the Cardinals' coaching staff that Wainwright needed to be taken out because his curveball wasn’t breaking, and his location was off -- brutal honesty that briefly had them at odds. Then, a couple of days later, there they were shoulder-to-shoulder, hanging over the dugout railing while trying to snag a foul ball with their caps. When Molina caught it just inches ahead of Wainwright, the pitcher flashed a disappointed look at the catcher the way a wife might glare at her playful husband. And much like an old married couple, Wainwright, 41, even has Molina, 40, liking his favorite brand of music -- twangy country -- these days.

Their bond -- sometimes loving, sometimes playful and other times brutally honest -- is so strong that they regularly refer to one another as brothers. Not only has their partnership allowed them to become one of the most successful batteries in baseball history, it has extended well beyond the games, the clubhouse hijinks and bus rides filled with stories, strategies and skull sessions.

Their families cherish a photo taken a couple of years back where Yanuell Molina and Morgan Wainwright, both then 2 years old, have their arms thrown across one another’s shoulders at a ball game.

“It’s a relationship that started as pitcher and catcher, baseball only and at the field only, to 19 years later doing Thanksgiving with him in his house in Puerto Rico and our kids playing and being raised together,” Wainwright, who is a native of Brunswick, Ga., said. “Things like that you can’t make up.

“Yadi and I started out as kids and now we’re old men, and we grew up together. I don’t know how many teammates we’ve seen come and go. We’ve seen guys traded, and we’ve played with lots of people, but we’ve always been together. We’ve won a lot together, we’ve lost some together and we’ve cried together. When you have those life experiences, you’re bound to grow close.”

Molina and Wainwright's friendship, one that has kept them together for 18 MLB seasons, hit a major milestone on Thursday with their 324th start together as a battery. That longevity drew them even with Mickey Lolich and Bill Freehan, who starred with the Tigers from 1963-75, for most all time. (Incredibly, Lolich and Freehan last started together on Sept. 8, the same date Molina and Wainwright matched their mark.) Already the most successful battery in baseball history with their 212 team wins in their collective starts, Molina and Wainwright will secure their place as baseball’s most durable battery.

“They don’t even have to put signals down, because they know what each other is thinking,” said longtime teammate Albert Pujols, marveling at their chemistry. “What we’re seeing with them will likely never be done again, because it’s hard for guys to stay together as long as they have. They’re incredible.”

Clearly, their partnership has stood the test of time, but has it been because they have had so much success? Or do they continue to have success at advanced ages because that bond has been so battle-tested through the years?

Wainwright and Molina are credited with 18 years of MLB togetherness -- service time that trails only the 19 years Mariano Rivera and Derek Jeter plus Lou Whitaker and Alan Trammell spent together -- but their relationship actually goes further back. They were Triple-A teammates in 2004, just months after Wainwright was traded from the Braves and after a then-20-year-old Molina impressed following his first big league camp.

“It’s been a long time since then; too many hits in the head for me to remember,” Molina said of his first time working with Wainwright.

What would follow over the nearly two decades together would be incomparable success. They have the fourth-most innings together (2,131 1/3) and the most in the rich history of the Cardinals. Among starting pitchers and catchers, their 212 team wins outdistance that of Warren Spahn and Del Crandall (202).

Molina has helped Wainwright win both as a catcher and a hitter. With 333 hits in games started by Wainwright, Molina has the most hits in AL/NL history by a catcher with the same pitcher. Also, Molina’s 19 game-winning RBIs are the third most by a catcher with one pitcher.

“Waino is not only my teammate and a friend, he’s like a brother to me,” said Molina, who earlier this week moved into second in AL/NL history in starts by a catcher with 2,098. “To do this with him is amazing.”

Then, there’s this fact that shows the strength of their partnership: Wainwright has been a much more effective pitcher while working with Molina. That has been especially true this season, with Wainwright going 8-5 with a 2.91 ERA with Molina behind the plate and 2-4 with a 3.93 ERA when Molina took time off with a sore knee. That was also the case in their first 17 seasons together: Wainwright’s ERA was 4.08 without Molina catching him and 3.22 with his favorite backstop.

“Dang, don’t be afraid to catch a little more Yadi,” Wainwright joked. “Some of it is coincidence, because I was hurt in 2017-18. Some of it isn’t, because we work so great together and we’re a team. Like Kevin Costner said, ‘We’re like a couple of old shoes together.’”

Their signature moment will always trace back to Oct. 19, 2006, at Shea Stadium when they worked together to cripple the Mets. After Molina hit a go-ahead, two-run home run in the ninth inning of Game 7 of the NLCS, Wainwright threw arguably the most important curveball of his lifetime when his big breaker caught Carlos Beltran looking to get out of a bases-loaded jam. Who would ever think of calling a curveball on an 0-2 count to one of the game’s most feared hitters and the bases loaded? Molina would, and Wainwright trusted him.

“That pitch,” recalled Molina, “was definitely one of our top memories.”

Weary from 19 years behind the plate and nine Gold Glove Awards, Molina has already announced this season will be his last. Wainwright, the owner of 194 wins and someone who might pitch beyond this season, gets offended when someone questions Molina’s candidacy as a Hall of Famer, saying, “When Johnny Bench says Yadi is the best defensive catcher all time, that’s good enough for me.”

Molina, who was coaxed back to St. Louis following a six-week sabbatical in Puerto Rico, wants this season to end the same way 2006 and ’11 did -- with a World Series win. And if the battery for that clinching out is Wainwright and Molina, the 5-foot-11 catcher will happily jump into the arms of the 6-foot-7 pitcher again.

“I’m so happy I get to spend this season with my brothers,” said Molina, lumping in Pujols. “We’ve got a bunch of memories, and winning championships are the best ones. Hopefully, we can do it again.”