Manchester United youngster Timothy Fosu-Mensah has expressed his gratitude to Louis van Gaal but said it is "unbelievable" he will now get the chance to also work under Jose Mourinho.

Fosu-Mensah, 18, made his United debut in February and also recently received his first call-up to the senior Netherlands national team, although he had to drop out due to injury concerns.

According to Voetbal International, his agents are currently negotiating a new contract at Old Trafford, and Fosu-Mensah, who can operate in defence or midfield, says he is excited about working under new United manager Mourinho.

"I've never heard a player speak badly about Mourinho," he said. "I'm curious -- I want to develop into a top player for Manchester United under him. That's the next step in my plan.

"You're 18 and you've had Van Gaal and Mourinho as your managers. Really, it's unbelievable."

After making his club debut against Arsenal in February -- a day he describes as "the best moment of my career so far" -- Fosu-Mensah's star has risen quickly. According to Voetbal International, Mourinho has already made it known he's looking forward to working with Fosu-Mensah.

"It can't go fast enough for me," Fosu-Mensah said. "All my life, I've set goals for myself. This season, I was playing for Manchester United's under-21s. It makes sense that the next step is making your first-team debut, doesn't it?"

Timothy Fosu-Mensah made his Manchester United debut against Arsenal in February. Matthew Peters/Man Utd via Getty Images

In the same interview, Fosu-Mensah also praised his compatriot Van Gaal.

"I can only speak for myself and, for me, Van Gaal was good, the best I ever had," he said. "Yes, he was present and he talked a lot, but he was like that with everyone, with the aim of improving you as a player. He succeeded in doing that with me. I can notice that about everything."

Fosu-Mensah also enjoyed working with Ryan Giggs, who was Van Gaal's assistant.

"Giggs talked to me a lot," he said. "For example, after the semifinal of the FA Cup against Everton, when I played well, but also caused a penalty. 'Stay on your feet in such a situation,' Giggs said. I learned so much from that."

He has also learned from his teammates at United.

"I listen to Michael Carrick, Chris Smalling and to the Dutch guys, Daley Blind and Memphis Depay," he said. "I sit in the dressing room and just listen to what everyone has got to say, and especially to our captain, Wayne Rooney.

"I remember when I conquered the ball in the semifinal against Everton in the 44th minute. I crossed midfield and tried to reach Rooney, but the pass was intercepted. Then Rooney came to me and said: 'Timothy, it's the 44th minute, almost half-time, keep the ball in the team at such a time.'"

Recalling his debut against Arsenal, Fosu-Mensah revealed he had not been entirely prepared for his promotion to first-team duties.

He said: "I came to the club before the game that Saturday, did what I always do, grabbed my breakfast, until Van Gaal asked me if I had my club uniform with me. 'No,' I said.

"About an hour later he came to me again. I was in the squad. He asked me if it was possible for my dad to go and fetch my club uniform."