Former Lions boss Sir Ian McGeechan expects Jonny Wilkinson to miss out on the tour of Australia, despite the fly-half's excellent form for Toulon.
The first game on tour takes place on 1 June, the same day as the French league grand final, in which Toulon are tipped to be involved.
McGeechan said the schedule made it difficult for Wilkinson "purely from a practical point of view".
"He won't have the chances to be really part of the build-up," said McGeechan.
"You've got everybody involved in that. If you've got players missing for two or three weeks out of that process, then it becomes very difficult."
McGeechan led the Lions to victory as head coach on the tours of Australia in 1989 and South Africa in 1997, as well as overseeing the 2009 and 1993 trips.
Wilkinson did not feature on any of those tours, making his England debut in 1998 before persistent injury ruled him out of contention for the 2009 squad.
But the 33-year-old has been a key player for Toulon, impressing ex-England team-mate Alex King, who believes the he "has got his game back to where it was pre-2003".
King, who is assistant coach at French side Clermont Auvergne, added: "He has led the Toulon team fantastically well all season. He has been the top points scorer again this season and he is a match-winner.
"He pretty much guarantees you 18-21 points per game. If you score a try on top of that, that is 26 points already and you are going to have to be a very good side to score more than that."
King, who will return to the Premiership this summer as Northampton's new backs coach, could face Wilkinson in the final of this season's Heineken Cup.
Clermont Auvergne entertain Munster in the first semi-final on Saturday before Wilkinson's Toulon face Saracens at Twickenham on Sunday.
The game pits Wilkinson against Owen Farrell, his successor as England fly-half and potential Lions rival.
Asked how Wilkinson had developed since they were England team-mates, King added: "Jonny has probably got better if anything.
"He has had an amazing run of games in France, he was blighted by injury in his last few seasons in England and I think now he has got his game back to where it was pre-2003.
"He has missed only a handful of games. He is managed very well in the south of France and I think he has got an excellent lifestyle down there. I think he is just loving his rugby and loving his life down there. It is obviously working because he is the star of that Toulon team."
Wilkinson, who kicked the winning goal for England in the 2003 World Cup final, joined Toulon from Newcastle in 2009.
He retired from international rugby in 2011 after winning 91 caps and has said he would relish the opportunity of being part of the British and Irish Lions tour this summer, although does not expect it.
Lions coach Warren Gatland said in December Wilkinson is in the frame for the Australia tour but admitted Toulon's success could hamper his hopes. with the French league final on 1 June clashing with the tour opener against the Barbarian in Hong Kong.
Wilkinson signed a new one-year deal with Toulon earlier this month, with them second in the French Top 14, one point behind Clermont.