O'Connell missed Ireland's win over Wales

The Munster player, who missed the 31-5 victory over Wales because of a shoulder injury, came through a full work-out on Thursday.

The return of O'Connell is the only change to the Irish side that beat the Welsh so convincingly in Dublin.

Johnny O'Connor is replaced on the bench by Mick O'Driscoll after picking up a groin injury in training.

Scotland have been the team of the championship Eddie O'Sullivan

Prop John Hayes, struck down by a viral infection in the aftermath of the Wales match, and loose-head Marcus Horan - stretchered off with a minor neck injury - have both recovered to take their places in the front row.

Victory on Saturday would see Ireland travel to Twickenham on 18 March for a Triple Crown, and potential Six Nations title, decider.

But first the Irish must dispatch Frank Hadden's rejuvenated Scotland, who have emerged as contenders themselves after shock triumphs over France and England.

"Scotland have been the team of the championship in that they were written off at the start in much the same way Wales were last year," O'Sullivan added.

"They're very single-minded in their job and play with a lot of passion and commitment, which has always been a hallmark of Scottish rugby.

"They've got back to where they want to be in terms of competing in Six Nations rugby. Frank Hadden obviously knows what he wants and is getting it out of the players."

Ireland team: Geordan Murphy (Leicester); Shane Horgan, Brian O'Driscoll (capt), Gordan D'Arcy (all Leinster), Andrew Trimble (Ulster); Ronan O'Gara, Peter Stringer; Marcus Horan, Jerry Flannery, John Hayes; Paul O'Connell (all Munster), Malcolm O'Kelly (Leinster); Simon Easterby (Llanelli Scarlets), David Wallace, Denis Leamy (both Munster).
Replacements: Rory Best, Simon Best (both Ulster), Donncha O'Callaghan, Mick O'Driscoll (both Munster), Eoin Reddan (both Wasps), David Humphreys (Ulster), Girvan Dempsey (Leinster).