91�ȱ�

Jamie Roberts is crucial to Wales' hopes in the 2015 Six Nations, says former England centre Jeremy Guscott.

Wales host England in the first game of this year's tournament on 6 February, and 91�ȱ� pundit Guscott believes the match will be "incredibly tight".

He says Racing Metro centre Roberts, 28, holds "a big key" for Wales.

"A lot depends on and a lot is riding on Jamie Roberts' performances for Wales. If he doesn't make errors, Wales do incredibly well," said Guscott.

Roberts was among Wales' star performers during their November Tests, which included the historic 12-6 win over South Africa.

But Guscott, who won 65 caps for England between 1989 and 1999, believes there is still room for improvement in his game.

"He's been worked like a donkey through 2014," said Guscott.

"He played all the games in the Six Nations and played every minute of the autumn.

"He carried well. His tackling was spot on percentage-wise. He just made a few more errors than a player of that quality normally would."

Former Cardiff Blues back Roberts and potential Wales centre partner Jonathan Davies both got the better of English counterparts in European competition at the weekend.

Roberts was man of the match in Racing's 32-8 win over Northampton, while Davies started Clermont Auvergne's 18-6 victory against Saracens.

"I did notice that Jonathan Davies ran through Brad Barritt at the weekend and Jamie Roberts had a stormer against Luther Burrell," said Guscott.

"But I don't think anyone is surprised that the Welsh backs have the advantage."