Jose Mourinho was taken aback by the "phenomenal" Henrikh Mkhitaryan goal that capped Manchester United's comprehensive win and ensured a chastening Old Trafford return for Sunderland manager David Moyes.
Initial struggles to break into the squad, never mind the line-up, have become a thing of the past for the talented Armenian, who has rapidly become a fans' favourite.
Mkhitaryan netted in a third successive match and few can have opened their United account with three better goals after he followed up his excellent solo goal at Zorya Luhansk and drive against Tottenham.
Back from an ankle complaint, the 27-year-old substitute met a cross from Zlatan Ibrahimovic with an outrageous flick towards the end of the 3-1 win against Sunderland.
"I have to watch back on TV because I didn't yet, but it looked for me phenomenal," Mourinho said of the beautiful, if in fact offside, goal.
"I think he scored in the right goal, the Stretford End, with the people very enthusiastic just behind.
"It was a great moment and for him important because he was going up and up and then the injury comes.
"He was out of two matches and he's back. And to be back not just (with) the goal, I think he also brought quality with his performance. I am obviously happy."
Mourinho believes United thoroughly deserved the Boxing Day win, having followed Daley Blind's first-half strike with a fine display after the break. Ibrahimovic provided the assist for the defender and crossed for Mkhitaryan, having coolly netted United's second himself.
The 35-year-old has been involved in 12 Premier League goals this season and Mourinho again said that his future will be at Old Trafford beyond the end of the season.
"I am not really surprised because he is a very intelligent guy and he's a very proud man," the United manager said.
"For him to decide to come to a club with the level of expectation of Manchester United and the most difficult league in the world for a striker, it is because he knows that he can do it."
Asked if the one-year extension clause beyond Ibrahimovic's initial one-season has been activated, Mourinho said: "Not yet, but it is activated in his brain and it is activated also in my decisions, the owners and the board's, so no problem."
Ibrahimovic will likely have another chance to shine against Middlesbrough on New Year's Eve - a match captain Wayne Rooney could miss having sat out the Sunderland win with a strained muscle.
Moyes' first return to Old Trafford since his sacking in April 2014 ended in disappointment, despite Fabio Borini's exquisite late consolation strike.
"I knew someday I would either come up against the Manchester United players or work with some of them.
"That's the way it has been for me and I've got to say I enjoy coming back, I've always enjoyed coming here.
"Hard place to come, hard place to get a result and it proved to be that again today."
Man Utd: de Gea, Valencia, Jones, Rojo, Blind, Herrera (Fellaini 84), Carrick, Pogba, Mata(Martial 74), Ibrahimovic, Lingard (Mkhitaryan 62). Unused subs: Smalling, Rashford, Romero, Darmian.
Sunderland: Pickford, Jones, Koné, Djilobodji, van Aanholt, Larsson (Khazriat 83), Denayer, Ndong (Loveat 86), Anichebe, Defoe, Borini. Unused subs: Mannone, O'Shea, Asoro, Honeyman, Embleton.
Referee: Martin Atkinson
Man of the match: Pogba
Match rating 7/10