Daniel Arzani's rapid rise has surprised Michael Jakobsen, but the attacker's former team-mate backed the Australia teenager to have a big future.
Arzani, 19, is already being linked with a move from Melbourne City to the Eredivisie after just 24 A-League appearances.
The talented winger impressed enough to earn a spot in the Socceroos' World Cup squad to be the youngest player at the tournament, and came off the bench in Australia's 2-1 loss to France on Saturday.
Jakobsen, now at Adelaide United after spending two seasons at City, said Arzani's quick progression had come as a shock.
"I'm a bit surprised to be honest," the former Denmark international told Omnisport.
"I think it's a good thing that they've taken some of the young guns and he has some X-factor or some abilities that some of the other guys in the team don't have. One-on-one he's very, very good.
"But there are some downsides when you play with a young guy and that's just how it is. I think it's a good thing that they've taken him early because he's just going to learn from it.
"If he's a man for the future, he can get a very good lesson out of this.
"It's not his last World Cup, so going into the following years, I think he will be one to watch for Australia because he has very big potential."
Arzani made his third appearance for the Socceroos in the loss to France, coming on in the 84th minute in Kazan.
Jakobsen praised the Iran-born teenager's character, but said it was vital Arzani – who scored his first international goal in a friendly against Hungary earlier this month – had good guidance.
"He's a hard-working kid and it's not often you see that when you have these big talents that are young," he said.
"They are [usually] like 'I'm so good', but Arzani has his head on in the right spot, so that's very positive.
"If he keeps his nose on track, he can make it very far, but it's important that he makes the right steps and the right decisions, so I hope for him he has someone alongside him to coach him in the right direction."