With tournament dark horses Belgium trailing to Algeria's first World Cup goal in 28 years, the former Everton midfielder came off the substitutes' bench to power in a header to equalise in the 70th minute.

Fellow substitute Dries Mertens drove in the winner 10 minutes later to give Belgium a winning start in Group H.

"Fellaini is one of the best headers of a ball in Europe, he brings a lot to the game in terms of his physical impact," said Algeria's Bosnian coach Vahid Halilhodzic.

"He was so dominant in the air that my players didn't have an answer to it. He's an extraordinary player who changed the game."

Fellaini spent five years at Everton before signing for Manchester United in September last year in a �27.5 million ($46.6m, 34.4m euros) deal.

But he made just 16 league appearances and failed to get on the scoresheet.

Belgium coach Marc Wilmots admitted that the second half introductions of Fellaini, Mertens and Divock Origi had been decisive in sparking a sluggish Belgium side who are many commentators' outsiders for the title.

"Mertens has speed on the wings, Origi has strength up front and Fellaini has physical force. This worked well," said Wilmots.

"Dries was dynamite on his wing and he has a nose for goal while Marouane was too physical for the Algerians."

Despite the high praise, 26-year-old Fellaini played down the tributes, preferring to give his teammates the credit.

"It was difficult but the most important thing is the win," said Fellaini.

"We were a little nervous, a little stressed. It's our first World Cup so it's normal. We played better in the second half and created lots of chances."

He also refused to see himself as the saviour of his team.

"The whole team was the saviour. The bench made the difference. My goal is good for me but especially for the team."

He also shrugged off any suggestions that Belgium should be considered as favourites for the World Cup.

"We are not favourites for the tournament. Brazil are favourites, they are at home and they have to win. The pressure is not on us."