Six Nations 2014: Sexton trains with Ireland ahead of Italy game

Paddy Jackson and Jonathan Sexton after Ireland's defeat by England

Jonathan Sexton took a limited part in Ireland training on Tuesday as the squad continued their build-up to the Six Nations clash with Italy.

Sexton, who suffered thumb ligament damage in the defeat by England, swapped fly-half positions with Paddy Jackson during Tuesday's session.

Ireland assistant coach John Plumtree said that a decision on Sexton's fitness will be taken on Thursday.

Peter O'Mahony remains a major fitness doubt for the Aviva Stadium contest.

Ireland assistant coach Plumtree revealed the latest scans on Sexton's thumb problem show no lasting damage.

Six Nations 2014: Ireland happy with Sexton fitness

The Racing Metro playmaker must prove his full recovery in "tackling and grappling" on Thursday, said Plumtree.

Racing Metro last week predicted the former Leinster star could miss between 10 days and six weeks but Ireland bosses quickly downplayed that estimation.

"Jonny trained today and he did really well," said Plumtree.

"He was sort of in and out with Paddy (Jackson) and Mads (Ian Madigan) so we'll make that final call on Thursday but he didn't look in too much discomfort at all."

Munster captain O'Mahony sustained a hamstring injury in the Twickenham game and his training on Tuesday morning was restricted to some running, as opposed to any contact work.

If O'Mahony does miss Saturday's game, Ulster forward Iain Henderson could be drafted into the starting line-up.

Brian O'Driscoll took a limited part in Tuesday morning's session but still looks likely to earn a world-record 140th cap this weekend.

O'Driscoll has been bothered by a calf injury since the England game but the Irish management appear confident that the 34-year-old will be fit enough to play.

The former Ireland captain swapped his centre position with emerging Connacht star Robbie Henshaw during Tuesday's session.