The 18-year-old, who signed for Borussia Dortmund just before the finals began, capped a fine display with an assist for Burak Yilmaz's opener at Stade Bollaert-Delelis in Lens.
"We've been impressed by him," he said. "It was an important decision, whether to play him or not. He's been like a saviour tonight. He's been valuable to us and I believe he will have a big impact in our team.
"Volkan Sen, Emre Mor, Burak Yilmaz - they all had a great game. The whole team defended very well, we were solid, we kept the ball. After Ozan Ozyakup came in, we had more chances, we had to defend at some moments but our goalkeeper had a good game. I'm totally satisfied."
Terim, who had questioned his team's commitment to their pre-tournament training camp in the wake of those opening two defeats, believes they could enjoy a repeat of their run to the semi-finals in Euro 2008 if they hold onto a place in the next round as one of the best third-placed teams.
"Let's wait until tomorrow night. If we advance, we can do what we did in Euro 2008," he said. "Our confidence is growing now and we still have some problems, but now it's easier to find solutions.
"It's not certain - I hope we won't go out. I would be really frustrated to be out. But if we advance, we will restart, reboot. I think we'll improve, my experience tells me that.
"I can say that I made some mistakes in the first two games. Tonight the performance was better. As I've always said, tonight was the right moment to give a reaction, to stand up. We gave a big reaction.
"We even had the chance to score more goals and go through tonight. We were criticised a lot, it's been hard psychologically. Now we have our confidence growing.
"The players did a good job. We shouldn't forget that Czech Republic came back from two goals down against Croatia, they are a difficult side to play against. Our formation, 3-4-3, worked very well."
Terim had singled out broadcaster TRT for their criticism prior to the match, and the former Galatasaray boss could not help but take a further swipe when asked if his pre-game comments helped his team.
"Yes, I think so. But I don't want to answer questions from TRT," he told the reporter in question. "Don't take it personally."