Fellaini has endured a miserable time since moving to Old Trafford last summer in a £27.5m deal but equalised for Belgium in their 2-1 victory over Algeria just five minutes after coming off the bench in the second half.
Jan Vertonghen, the Tottenham Hotspur defender who gave away the first-half penalty that handed Algeria the lead, said Fellaini was “very important” to the national side.
“I know there has been a lot of pressure on him from the fans in England but in Belgium he always does well and scores goals,” said Vertonghen. “I’m very pleased for him and I gave him a little hug after the game because I know that goal meant a lot to him.
“Marouane is a very cool guy. The pressure doesn’t really bother him too much. We know how to use him and I don’t know whether they do in his other team.”
Belgium’s captain Vincent Kompany said Fellaini’s qualities had always been apparent in a national shirt.
“Fellaini is a terrific player and any player in his first season at a new club, it can be tough. You have to grant players a couple of seasons before you can judge someone. For us, with Belgium, he has been doing it time and time again. Players like Dries Mertens as well are our weapons coming off the bench.”
Fellaini, who was the only major incoming transfer at Old Trafford last summer but faces an uncertain future under United’s new manager Louis van Gaal, said that Belgium’s substitutes had made a “big impact” on the game. Marc Wilmots introduced Mertens, who scored the winner, at half-time and Fellaini 20 minutes into the second half.
“Everyone knows we have good players, we have a good team, but for the first 30 minutes, we were just so nervous, there was too much stress. I think that is normal for the first World Cup together but in the second half we showed the character of Belgium and we played very well,” he said.
“It was a great goal, it was great for me and for the team. It’s not been the best season for me but football is like this. It is a boost for the confidence of the Belgian team. Algeria made it so tough, but we showed our character and ability.”
The highly fancied Belgians, who struggled in the first half against a well organised Algeria side, face Fabio Capello’s Russia in their second game on Sunday. Kompany admitted nerves played a part in their unconvincing first-half display against Algeria.
“It was the very, very first minutes of any World Cup ever for this generation of Belgian players, all of the players except for Daniel Van Buyten have never been at a World Cup,” he said, admitting that the pressure to perform had an effect.
“Of course for those first 15 minutes, however much experience you have in wider football – I remember even Lionel Messi saying how he had felt the pressure when he first played at a World Cup – so how is it possible for us not to feel it?”
But he said he was proud of his teammates for not panicking when they went behind and for slowly working their way back into the game.
“It means a lot that we overcame a difficult start but as much as it means, we remain calm for the rest of the campaign as well, we know it will be tough against Russia. The biggest mistake we can do is underestimate these teams. Hopefully we’ll do our job and we can qualify and like any team, grow in this tournament.
“After 15 or 20 minutes we got control of the game and then conceded at that moment. We never panicked, we stayed calm. We actually had these kind of scenarios quite often in the qualifiers as well, so that helps.”
Romelu Lukaku, who struggled in the first half and was withdrawn after an hour, said the team was not dynamic enough in the first period.
“We played too slowly in possession in the first half, it was not dynamic enough but in the second half, it was much quicker, we got more crosses in the box and we scored from one,” said the Chelsea striker, who spent last season on loan at Everton.
“It has been so long for us to wait to play at a World Cup and we have a young team as well so we had difficulties in the first hour of the game but then we took it into our hands like a big team should do.”
Lukaku predicted Belgium would learn from the experience and improve as the tournament progressed.
“We showed patience. Most of the players who started were playing for Belgium at 16, 17 or 18. We have shown we can be aggressive, we have shown that even though we are young, we have experience,” he said.
“I think we can play well against anyone – it was good to win and now we can grow into the tournament.”