The Brighton & Hove Albion midfielder picked up the ball 25 yards out after Viktor Gyokeres' effort was cleared off the line, and powered the bouncing ball home to set Sweden on their way to victory.
But Ayari held his hands up almost apologetically as his teammates surrounded him. His lack of celebration was out of respect for his family - his father, Azzouz, is from Tunisia.
Externally, he was not showing much emotion, but it was clearly a special moment for 22-year-old, who rejected the chance to represent the North African side, something his father supported.
"It's incredible, a feeling you can't describe," Ayari said after the game.
"You've dreamed of a lot, but this is something you never dreamed of. It was very emotional to play against Tunisia, who I feel so much for."
Ayari did give himself the freedom to celebrate his second goal, the final kick of the game, another sweet strike from outside the box that meant he perfectly bookended the Swedish display in Monterrey which silenced many of the squads' doubters.
“When no one believed in us, the whole group came together and believed in us,” said Ayari.
Isak happy to play his part
Between the Ayari goals, there was one each for Alexander Isak and Viktor Gyokeres, the star strikers who started up front together for Graham Potter's side.
Isak scored a wonderful solo effort, cutting in from the left wing to make it 2-0, before Gyokeres' goal made it 3-1, on hand to finish well after Isak had wrestled possession back high up the pitch.
The Liverpool striker is fully aware of the expectations that he and the Arsenal man have on their shoulders, but the main thing for Isak is to play their part for the team, like anyone else.
"We (Gyokeres and I) are supposed to be the difference. We are supposed to counter and do the maximum and then recover a bit. When the two of us play together, it doesn't mean that we have to play a certain way or anything. The most important thing is that we contribute to the team."
Despite the experience at the highest level in club football that he and many of his teammates have, Isak suggested that the World Cup is another level, and getting off to such a positive start cannot be taken for granted.
"This effort means a lot. It's a different environment here because we're playing for Sweden, for our country. It feels incredible. There are many of us who are World Cup debutants, and to be able to debut in this way is a bit surreal, actually."
Sweden will be hoping to build on their great start when they face Netherlands on 20th June, 19:00 CEST.
