Drew Smyly didn’t know the door to his future was opening.

But it was.

Or, rather, was about to.

He was watching TV on the night of Dec. 2.

“I don’t remember what was on,” Smyly said. “It was pretty much an ordinary night. Then the phone rang.”

It was his dad.

“Did you see what the Tigers just did?” Drew’s father asked him. “They just traded Doug Fister.”

With that, of course, an instant vacancy was created in the Tigers’ rotation — but just as quickly, it was filled by Smyly, the starter-in-waiting.

In fact, it was the moment for which the left-hander had been patiently hoping — but one he was confident would come sooner or later

It initially felt strange when it did, though.

“We all liked Doug,” Smyly said of Fister. “It was tough to see him get traded because he was a great teammate. At the same time, though ...”

At the same time, opportunity had suddenly arrived — no hemming and hawing necessary.

“So it was bittersweet,” Smyly said. “I was sorry and excited at the same time.”

Throughout his successful full season as a relief pitcher, the Tigers never had stopped looking at Smyly as a future starter.