(John McDonnell/The Washington Post) (John McDonnell/The Washington Post)

On June 15, 1989, Adam Oates and Paul MacLean were traded by the Detroit Red Wings to the St. Louis Blues. Tuesday night they’ll stand behind opposing benches and coach against each other as the Capitals visit the Ottawa Senators

Oates and MacLean played together on a line with Rod Brind’Amour that first season with the Blues and helped each other through the transition with a new team

“You got a buddy when you go into that strange locker room. You got someone with you so you got a little bit of an allegiance,” Oates recalled Monday. “But we were both pretty sour at the time when it happened. We liked Detroit. And we got traded in the summer, and it was a shock. It was definitely a shock for me.  And I know he liked it there as well. But it’s a part of the job.”

The two crossed paths again in 2002-03 when Oates was playing for Anaheim while MacLean was an assistant coach for the then-Mighty Ducks. Oates said he saw an eventual head coach in MacLean, who was a finalist for the Jack Adams Trophy after his first year with the Senators in 2011-12.

Nest mustache in hockey? You be the judge. (Sean Kilpatrick / Associated Press) Best mustache in hockey? You be the judge. (Sean Kilpatrick / Associated Press)

“He’s a smart guy. And he’s very …level-headed,” Oates said. “He’s the same guy every day. He’s not too high or too low. I thought he’d be a good coach.”

And he has the best mustache in hockey, right? “If you like mustaches,” Oates quipped.