Duran was read the riot act by Emery after making clear on his social media channels last month that he wanted to join West Ham, who had shown an interest in signing the 20-year-old.
But the clubs could not agree a fee and 19 minutes after replacing Ollie Watkins, Duran scored the winner – before appearing to apologise to the Villa fans after he had celebrated. He also seemed to indicate that he would be staying at Villa when he pointed to the ground.
Emery said: ‘We know how much we believe in him and if he leaves it’s because there is a very good offer because I want to keep him.
‘He is not as consistent as he could be and sometimes it’s difficult to accept certain mistakes. But we have to accept them in cases like these because he is a very young player.
Duran's goal in the 79th minute proved to be the winner for Aston Villa against West Ham
‘He has to try to get balance in everything. We have been working with him for a year and a half. I have been very committed to get the best from him as a player and even as a person.
‘He has to play, he has to be ready to train every day like he was doing the last week and like he played today. We need two strikers and both have to have good performances and good commitment to play like they both played today.’
It remains clear that if Villa could do a deal for Duran that allowed Emery to sign a forward he prefers, they would look closely at it.
Whether this can happen with less than two weeks of the summer window to go is another matter entirely. Questioned on Duran, Lopetegui would say only: ‘I’m not going to talk about individual players for the opposition.’
This was Lopetegui’s first official game as West Ham boss, and he handed starts to only two of the eight players the club signed this summer.
He admitted: ‘A lot of the signings arrived late and are not ready for a high rhythm and a lot of minutes. We had players in the starting XI who were not ready for 90 minutes either and we had to change important players in the last 15 minutes.’