Aston Villa had scored only once in their first four league games and went into the extended international break with the win they needed, having now taken three victories from their last four matches in all competitions.
Manzambi broke the deadlock from close range in first-half injury time. He then set up Nicolas Jackson for the second on 67 minutes, before Emiliano Buendía added a third and Conor Gallagher and Jan Paul van Hecke pulled two back for the hosts late on.
Speaking to VillaTV after the match, the 20-year-old struggled to find the words, and singled out team-mate Boubacar Kamara for his part in the opener:
“I have no words for that, and I hope that's not my last goal!
“I saw Bouba (Kamara), he wanted to shoot! I had a good position, and then I was alone.
“I just took the ball and shot, and for me, the emotions were very amazing – for the fans, for me. I have no words for that.
“For me, that was very important, but I heard the fans sing for me. They have good music for me! And if I can give more goals, I (will) do that.”
Manzambi joined from SC Freiburg on 17 July in a club-record deal worth £59.5 million including add-ons, and he is one of 10 players Villa have signed this summer. He was named the Europa League's Young Player of the Season when Freiburg lost the final to Villa in Istanbul, and then scored three goals as Switzerland reached the World Cup quarter-finals.
He says the move is feeling more comfortable by the day:
“I feel very confident, because the team will help me. The first day, until today, they helped me every day.
“I am a young player in the dressing room. Really, I am very, very happy because they helped me every day, and that's very good for me.”
He was equally clear about what the result meant for a squad that had yet to win in the league:
“For us, that was very important, this win, because we know we don't have a win this year, so before the national team, that was very important.
“We know (when) we play away, that's always difficult in the Premier League, and with their fans, they can push, and for us it was very important that we stayed strong and we won.
“We can go happy on the national team, and when we come back, I hope we do like today.”
Villa's next league match is at home to Brentford on 10 October.