Former Ireland international Isaac Boss believes Johnny Sexton would offer greater physicality against France, but says that in-form Paddy Jackson could well retain the out-half jersey.

Sexton has yet to feature in the Six Nations this year as he continues to work his way back to full fitness after a calf injury.

The Ulster out-half, who has started seven of Ireland’s last nine test matches, including the wins over South Africa and Australia, has continued his development at international level and like the team itself, has grown into the tournament.

He was impressive in patches in the try-scoring defeat to Scotland, and was in sublime form in the rout of Italy, equalling the Six Nations record of nine conversions in one match in a flawless kicking display.

Jackson was just as comfortable with ball in hand and is now giving Joe Schmidt a real selection headache for the clash with Les Bleus in less than two weeks.

The Ireland head coach has intimated that he won’t release Sexton to Leinster to get provincial game-time this weekend, meaning the pair are likely to go head-to-head in training to persuade Schmidt of selection.

“It’s a tough one. He [Johnny] hasn’t played a lot of game-time lately and Paddy’s been going very well there,” Isaac Boss said on Against The Head.

While Jackson has become an assured performaer at the highest level, Boss believes his former Leinster team-mate brings more defensive prowess to the team than his young Ulster rival.

“He’s a bit more physical and bigger, which might be needed against the French.

“If he’s [Sexton] fit, I’m not sure to be honest...I think Paddy Jackson could get the start.

"Paddy’s put himself in the front running by being fit and available and playing well.

Fellow analyst Donal Lenihan says that while it would be a “huge ask” to select Sexton – he has played little more than 100 minutes of rugby since November – his detailed understanding of Schmidt’s game plan could sway the decision provided he is fully fit.

“He as a track record of being able to come back into international rugby from that position,” he says. “It’s a great position for Ireland to be in.

“Can you imagine Johnny Sexton coming off the bench with 25 or 30 minutes to play?

“Personally I think he’ll start Johnny Sexton.”