Chelsea head coach Thomas Tuchel lauded "world class" Romelu Lukaku and praised the star's off-field impact after leading the Champions League holders past Zenit 1-0.

Lukaku was the difference on Tuesday, scoring his first Champions League goal for Chelsea, who opened their title defence with a hard-fought victory at Stamford Bridge.

After scoring a brace against Aston Villa in the Premier League on Saturday, club-record signing Lukaku backed that up with a towering 69th-minute header against the Russian champions in Group H.

Lukaku has scored four goals since arriving from Serie A champions Inter and Tuchel hailed the in-form Belgium international.

"The performance of Romelu was not easy. We didn't create many chances for him, we did not create many deliveries. But he's the type of guy who doesn't lose confidence and belief. And that is why he is here and makes him a world-class striker," Tuchel said during his post-match news conference.

"You don't find many strikers of that quality and the guys who are there to score regularly for their teams are so, so important. There are not many goals in football and goals change the momentum of the match. It gives the whole team a lot of belief that maybe one half chance, one chance is enough for him to score.

"It's not the only talent he brings, he brings belief, he himself has the belief and he takes the pressure off the shoulders of other guys around him. He has the personality not to be impatient or lose confidence. He does what he does at a very high level and we are very happy he’s with us. There are a lot of reasons we are maybe not at our top level at the moment. But right now with pre-season, new guys coming in, international breaks, and so on, I am happy with how we play and find us very competitive. We know how to handle difficulties during matches and today I liked what I have seen on the sideline because I felt the energy and the effort.

" They are a strong opponent and we have accepted and respect that. It was a tough [Aston] Villa team at the weekend and a tough Zenit team today. They changed their line-ups, their mentality when they arrived when they played us, we need to adapt and find solutions. This is what we do at the moment."

Only Bayern Munich's Robert Lewandowski (22), Borussia Dortmund sensation Erling Haaland (20) and Manchester United attacker Bruno Fernandes (17) have scored more goals than Lukaku (14) in major European competition since the start of 2019-20.

Lukaku's 14 Champions League goals have come in his last 14 appearances.

Tuchel added: "He was the type of guy we were missing in our team, the profile, but not only for the talent but also for his personality. The guy is a super humble guy, loves football, loves to train, is such a good communicator in the dressing room, and is open to everybody. That creates a certain atmosphere and energy around him within the team that we are proud of and what we want to have because we believe in it.

"The atmosphere and the spirit last year took us very far and it's important we have it again. We have it with Romelu because he loves Chelsea, he knows Chelsea, he knows what this club is all about. As I said, he is not shy to speak out loud that he’s here and to help with his goals. If we miss him for one game, or hopefully not more games, we will try to find different solutions, maybe the style will be different in how we create chances.

"But now we have him and we are very pleased that he can show these things because he gives us belief and everybody around him a lot of confidence. It is the best start for strikers to score, to be decisive. There is no talk, no video of any coach in the world that can have the same impact."

"It feels really good," Lukaku told BT Sport. "I'm really happy with the win. We kept the game under control. We have to keep growing. I think today was a better performance than on the weekend. I'm really happy with the win and really happy with the goal."