London, Jul 16 (IANS): Former England captain Michael Vaughan and Australian spin legend Shane Warne feel that maverick all-rounder Kevin Pietersen will be England's x-factor in the forthcoming Test series against India.

Pietersen had a quiet Test series against Sri Lanka, scoring just 162 runs from three matches. But his valuable knock of 227 runs in the second Ashes Test helped England win the series Down Under.

Vaughan feels that former England captain Pietersen's form will be important for the team against India.

"His Test form is not a massive worry. In an x-factor series against India, which will bring big crowds and a buzz, I think he will perform," Vaughan was quoted as saying by the Daily Telegraph.

Warne feels that Pietersen can provide the thrust if England want to snatch the No.1 Test crown from India.

"If Kevin Pietersen finds his form again and provides that x-factor, then there is no reason why England can't become the No.1 team," said Warne.

Pietersen had admitted that the draw of luck hasn't particularly helped him recently. But he was looking forward to a big knock.

"I feel 100% that I'm on the brink of a big score. I've felt better and better. But the way that I play, looking to score and be aggressive and take the attack to the opposition, you are going to have good days and bad days. I've just got to keep playing the way I play and, if the way I'm playing at the moment is anything to go by, I'm very happy," he said.