Former F1 champion Sir Jackie Stewart has said he feels the sport needs to welcome a new title winner in 2014 to help 'liven things up' after four years of success for Sebastian Vettel.

The Red Bull driver romped to the title again last year in dominant fashion but faces a huge challenge to make it five championships in a row given the change in regulations for the season ahead.

Speaking to reporters, Stewart - a three-time winner himself - joked that Vettel was 'getting greedy' and said it would refreshing for a new champion to be crowned this year.

"I think it would be better, I think it would liven things up," he was quoted by Reuters. "It would be refreshing. Four times is a bit greedy!

"[But] nobody is up there forever. The world moves on and I'm sure that will be the case. I don't know if it will be next season.

"Red Bull are pretty impressive and they've now got more money coming in from sponsors than they have from Red Bull, because they are getting TV."

While he tipped the likes of Fernando Alonso and Kimi Raikkonen to push Vettel for the title, Stewart said there was one man who should be firmly in the mix for honours.

"I think Lewis Hamilton is the fastest driver in the business," he said. "Just sheer speed. When he puts a quick one in, he's the master at it."