The Swedish youngster was a second-half substitute and helped Spurs fight-back from 0-2 down to earn a point for the hosts.
Postecoglou said afterwards: "Lucas was great. He has been great but he has played a lot and we've just got to be mindful of that. He's becoming an important part of our team. I thought he made a real big impact when he came on.
"Like I said we were sloppy when we were on the ball in the first half and he’s one who takes a bit more care with it. He's a technician and he carries the ball really well. I thought he and Sonny (Heung-min Son) made a really good impact when they came on."
On the spirit shown late on, Postecoglou also said: "You can imagine the noise around us if the players didn’t respond. Thursday is obviously a massive game for us and at least from that perspective, and even for the players themselves, we've obviously got a challenge on Thursday night (AZ in the Europa League) but they overcame a fairly big challenge today and hopefully we show the same kind of mindset."