Gombau is steadfast in his commitment of holding on to the player unless the interest from the Amsterdam Arena is serious.

Having come on as a substitute to score in the Reds' 2-0 win over Perth Glory last weekend, Mabil started and was a lively presence again as Adelaide came from behind to defeat Melbourne City 2-1 on Friday.

Speaking after the match at AAMI Park, Gombau made it clear the Young Socceroos star would only be leaving South Australia on Adelaide's terms.

"This is true, Ajax and another club contacted us (asking) to send him on a trial," he said.

"What we want to know is exactly which intentions they have, if really they know the player, what they want, why they ask for him and these things. Because in the end to go and make a trial is easy but what we want (to know) is if their interest is real. And then we'll prepare the player to go."

According to Gombau, Mabil must become not just a regular but a genuine star at Coopers Stadium if the 19 year-old is to earn a dream move overseas - no small task given the abundance of attacking talent in Adelaide's squad.

"First he needs to show here that he's ready to go to Europe," he said.

"You cannot go to Europe if you are not an important player here, if you are not one of the best in the league. This is what I say to him. If he proves this, if he do this, for sure, opportunities will arrive.

"What you cannot do is not play, go to Europe and expect to play there. He's a good kid, he's working hard. His dream is one day to be a player in Europe, he needs to work hard and we will help him all we can. Our aim as a club is to create players."

Gombau indicated that the A-League break for January's Asian Cup has been mooted as a potential opportunity for Mabil to go on trial, but said his preference is for any such journey to be undertaken at the end of the season.