The 18-year-old had a big hand in the Reds' first goal and his performance earned him the Man of the Match accolade both from United fans on Twitter and Sky Sports.
He also won plenty of praise from manager David Moyes, whose second-half tactical switch – moving Januzaj from a central role behind the striker out to the left wing – yielded immediate results.
"Everybody can see what a player we have on our hands," said Moyes. "He can play all the positions [up front].
"He played behind the striker for most of the game at Sunderland and we thought he was terrific there so we started him there today.
"We were hoping he might have created just a little more for us, maybe crafted a few more opportunities, but at half-time I swapped him to the left wing and it made a big difference."
Given his age, Januzaj's confidence is hugely impressive. He never looks fazed or overawed by the occasion, and when the going gets tough he keeps demanding the ball.
"He's been like that since day one," Moyes revealed. "I speak to him a lot and he tells me he'd have no problem playing anywhere. He's not a nervous boy.
"He needs teaching and understanding because he's still learning the game in a lot of things he's doing but his natural talent and ability is up there with the best and I think in time he will be that."