Former England international Jonny Wilkinson could miss Toulon’s Heineken Cup semi-final against Irish side Munster on 27th April.
The fly-half was taken off after just 28 minutes in Toulon’s 29-14 victory against Leinster in the last round of the European competition on Sunday.
“I’ve had this for the past two weeks and felt it immediately when I went to kick,” Wilkinson said.
“I’ll take it day-by-day and hour-by-hour as I would love to play Munster.”
Assistant coach Pierre Mignoni said: “Jonny has aggravated the same hamstring as before but did not look too serious.
“Hopefully he will be OK and back in one or two weeks but we have to wait and see.”
Despite being England’s highest points scorer, Wilkinson has been plagued by injuries for much of his career.
If he does play at Toulon’s Stade Mayol in three weeks’ time, it will be only his fourth European semi-final appearance, all with the French club.
And it could also be his last, with rumours circulating that the 34-year-old plans to retire at the end of the season.
Toulon won the Heineken Cup for the first time in their history last season, beating fellow French side Clermont Auvergne 16-15.
They will be hoping to become only the third club to win the tournament two years in a row, after Leinster and Leicester Tigers.
One man whose European playing career did come to an end in the quarter-final was Irish captain Brian O’Driscoll.
The 35-year-old was hoping to add his fourth Heineken Cup trophy to the Six Nations he won in March.
The Leinster centre announced his retirement from the game before the start of the season, ending a 14-year career with club and country
He played his last of his 133 games for Ireland to win the Championship, beating France 22-20.
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