Justin and Hailey Bieber look like a happy couple again … and all it took was some front-row tickets to an important hockey game for his favorite team.

The Biebers are all smiles Sunday night at Scotiabank Arena in Toronto, where they are watching Justin’s Toronto Maple Leafs take on the Florida Panthers in a win-or-go-home situation.

Justin and Bieber are cheesing from their seats right behind the Maple Leafs’ bench … and she’s got on a Maple Leafs jacket while he wears a bucket hat and sunglasses indoors.

The Biebs is having a Sunday fun day for the books … earlier in the day he posted a rare photo with his father, bragging he beat his old man in a game of golf.

As we reported … Justin and Hailey did their own separate things Friday in Los Angeles, but 48 hours later they are looking like two peas in a pod.

We have a new documentary — “TMZ Investigates: What Happened to Justin Bieber?”, steaming now on Hulu — where we look at Justin’s financial issues, mental health, marital struggles and more.