The youngster has a been a big success story in a difficult season for Spurs.
Explaining why Spurs aren't shopping for a senior midfieder, Postecoglou said: “Maybe a lot of that is because with guys like Lucas, Pape (Matar Sarr), Archie (Gray), we see a lot in them to become a good midfield dynamic for us in how they can all bring something different to the table.
“Then with (Rodrigo) Bentancur, (Yves) Bissouma and (James) Maddison, and now with Wilson (Odobert) coming on — and Deki (Dejan Kulusevski) will definitely end up in there — we’ve got some strong midfield options.
“While there’s work going on in the background around summer, I do feel that when we’ve got everyone available and the squad is at good strength, with that development, particularly with Lucas, we’re getting to a position where we’re stronger in that area, for sure.”