"I was at the club for two and a half years, I didn't break into the first team. I was inspiring myself to try and break into that first team but it didn't happen," Matondo said.
"Of course, Manchester City's a great football club, great players, great manager, so there's nothing I could say bad about them. I'm just grateful that Schalke said they'd give me opportunities and that's what I'm getting right now, more than I would have at City."
"He was born in 2000. We have followed the player for a long time, and we had a good feeling about him from the start," he said.
"He's a very young player. We and he need patience."
On Schalke's chances of overcoming the reigning Premier League champions in the last-16 clash, Tedesco said: "Of course we believe in a victory. We are the underdog, we are clearly not the favourites.
"But nevertheless, we deserved to make it through to the last 16 and were competitive against strong teams in the group phase. We managed to achieve 11 points in our group.
"But we know Manchester City are a strong team to oppose. We need to have our best day."
Tedesco also confirmed that club captain Ralf Fahrmann will get the nod over Alexander Nubel in goal for the German giants against City, while midfielder Nabil Bentaleb is expected to be available.
"That's the good news of this week that Nabil Bentaleb has no pain anymore," he added, having recently called into question the former Tottenham player's attitude. "He is without pain so should be fit."