Jose Mourinho believes Romelu Lukaku's "love" for West Brom was the reason behind his muted celebration during Manchester United's 2-1 win at The Hawthorns.
It was a hard-fought victory for United as Gareth Barry's 77th-minute tap-in made for a frantic finish after first-half goals from Lukaku and Jesse Lingard.
Lukaku's brilliant header sent United on their way, though the Belgian's celebration was similar to his reaction after scoring the winner against Bournemouth in midweek.
However, Mourinho said it was down to the fact that Lukaku enjoyed an impressive 2012-13 campaign with the Baggies on loan from Chelsea, while the United boss also put his own lack of enthusiasm after the opener down to maturity.
When quizzed by Geoff Shreeves on Lukaku's celebration, Mourinho said: "I didn't celebrate too. Nobody was happier than me, it's just a question of profile.
"I am happy, I'm happy with the victory. But 15 years ago I look at myself celebrating goals and now I feel a little ashamed with that, but with maturity you go into levels where you control your emotions better. Unless, I repeat, you score a winning goal in the last stage of a game.
"Also, I think Romelu had the fact that he was a happy kid at West Brom. He was a kid that was given all the conditions here to have the evolution he had. So probably in the back of his mind is that love for the club."
It was Lukaku's fifth goal against his former employers, and the header came before Lingard's deflected strike put United in control before half-time.
However, West Brom pushed up after the break, and scored their first goal of the Alan Pardew era when Barry tapped in after scrappy play from a corner.
Mourinho said his United side had anticipated West Brom's physical response, referencing former boss Tony Pulis as a reason for their danger at set pieces.
"We were the best team, but I knew before the game that this team would be really dangerous on set pieces," Mourinho added.
"Tony is an expert on that, his teams are strong physically, and we knew they could create that problem any time.
"We controlled the game for a long, long time, and then of course Alan reacts, he makes a few changes to give them more width. We had a few chances to kill the game, but when you don't, I knew they would react. That's normal.
"I don't think [our concentration dropped]. Probably less ambition, and that intensity we had in the first half we lost in the second half.
"They are powerful in the air, they have giants, they have aggressive people - even our goalkeeper with the ball in his hands is kicked. We knew that, the good thing is that after their goal we controlled the game again. They didn't have much more after that."