Jonny Wilkinson will discover if he will play again this year once he has undergone exploratory surgery on his dislocated left knee this weekend.

The operation, the fifth Wilkinson will have had since drop-kicking England to World Cup glory in 2003, should determine the extent of the injury he suffered against Gloucester this week.

Only then will it be known whether the Newcastle fly-half requires a further operation just to repair damaged muscles or complicated surgery to stabilise the whole area.

But one expert said: "I was terrified when I first heard of the injury because, in a worst case scenario, a bad dislocation is career threatening.

"However, it is vital that the exact amount of damage is assessed. It is impossible to speculate on the length of time Wilkinson will be out until we have a clear idea of the actual damage.

"In some ways it helps that it is his kicking leg because the standing leg of a top-class kicker takes all the pressure."

If it is only muscle damage the No10 could be out for four months.

However, if the operation reveals substantial damage then Wilkinson will be in danger of missing the Six Nations Championship as well as next month's internationals at Twickenham.