Isaac Boss is in line to become the first player to represent two Irish provinces 100 times when he lines out for Leinster against Glasgow Warriors tomorrow evening in Scotstoun Stadium (kick-off 5.15pm) in the first round of the Guinness PRO12.
After 108 appearances for Ulster, it was against this weekend's opposition Glasgow, but in Firhill Stadium, that he made his debut in September 2010 with an 80 minutes, try-scoring display.
He went on to play a further 28 times for Leinster in that debut season scoring a further three Pro12 tries and added to a memorable first season with a Heineken Cup medal from the final against Northampton.
This weekend Boss lines out in the familiar No 9 jersey, with Jimmy Gopperth outside him at 10 in what is Leinster's first competitive fixture after two pre-season friendlies against Northampton Saints and Ulster.
In the pack, Sean Cronin makes a welcome return after undergoing surgery earlier in the summer, with international colleagues Cian Healy and Mike Ross either side.
In the second row, Ben Marshall starts his first Pro12 game since February 2013 after an injury ravaged season last year, with Mike McCarthy starting his second season with Leinster beside him.
Having led the team out last weekend in Tallaght Stadium, Sean O'Brien is once again selected to captain the side from the base of the scrum with Dominic Ryan and Shane Jennings getting the nod at six and seven.
Noel Reid and Brendan Macken start in the centre, hoping to take their end of season B&I Cup form with them into the league. St Mary's Darragh Fanning starts on the left wing with Fergus McFadden again selected on the right.
Zane Kirchner who scored five tries in his debut season, starts at full-back.
The game tomorrow will be televised live on SKY Sports.
Leinster: Zane Kirchner; Fergus McFadden, Brendan Macken, Noel Reid, Darragh Fanning; Jimmy Gopperth, Isaac Boss; Cian Healy, Sean Cronin, Mike Ross; Ben Marshall, Mike McCarthy; Dominic Ryan, Shane Jennings, Sean O'Brien (capt).
Replacements: Bryan Byrne, Jack McGrath, Tadhg Furlong, Tom Denton, Kevin McLaughlin, Luke McGrath, Ian Madigan, Mick McGrath.
Louis Ludik, Franco van der Merwe and Wiehahn Herbst will make their competitive debuts for Ulster, against Scarlets, at Parc Y Scarlets, tomorrow afternoon (kick off 2.40pm).
The province travel to Wales to take on a Scarlets side who beat Gloucester last weekend and who have a squad packed full of internationals.
Ludik, who joined Ulster in the summer, starts the game at full-back. Michael Allen is selected on the right wing with Jared Payne and Stuart Olding picked in the centre.
Craig Gilroy starts on the left wing with Ian Humphreys and Paul Marshall maintaining their partnership in the half-backs.
Up front, Callum Black starts at loosehead, Rob Herring, who won his first cap for Ireland in the summer, is selected at hooker and new summer addition, Herbst, is named at tighthead.
Ireland’s Dan Tuohy and Springbok Franco van der Merwe are paired in the second row, while there is an all Ireland international back row with Robbie Diack, Chris Henry starting either side of captain Roger Wilson.
John Andrew is selected among the substitutes and is set for his first competitive appearance for Ulster.
Ireland international Luke Marshall and IRUPA Players’ Player of the Season for 2013/14, Andrew Trimble, are also selected on the bench.
Ulster: L Ludik, M Allen, J Payne, S Olding, C Gilroy, I Humphreys, P Marshall; (1-9); C Black, R Herring, W Herbst, D Tuohy, F van der Merwe, R Diack, C Henry, R Wilson (Capt).
Replacements: J Andrew, A Warwick, D Fitzpatrick, L Stevenson, N Williams, M Heaney, L Marshall, A Trimble.
Three debutants have been named in the Connacht side by head coach Pat Lam for their opening tie against Newport Gwent Dragons at the Sportsground on Saturday, kick-off 5pm.
Lock Quinn Roux, scrum-half Ian Porter and wing Niyi Adeolokun all make their first competitive start for the Westerners.
Jack Carty has been handed the reins at outhalf for the opening fixture while Shane Layden, from Carrick-on-Shannon, has been named at full back.
The 21-year-old academy back made a substitute appearance against Leinster in October 2011 but has battled with injuries in recent years.
The former minor Roscommon footballer has trained with the senior squad all summer to earn his place in tomorrow's starting line-up.
Up front, John Muldoon will captain from the blindside in a back row with fellow Galway man Eoin McKeon and New Zealander Jake Heenan, who makes a welcome return following surgery back in February.
From the bench, Conor Finn from Ballinasloe is also in line to earn his first competitive cap.
Commenting on team selection and the opening game, head coach Pat Lam said: "It's a very young side throughout but having the experience of leaders John Muldoon and Nathan White on the field will be invaluable.
"We have prepared well but we know Dragons will be no pushover. They have recruited well in the summer and are coming here on the back of a huge win last week against the Northampton Saints, the current Premiership champions who had their full squad out.
"That shows exactly where they are at and they'll be tough opponents for a lot of teams this year including us tomorrow.
"But we are still confident of getting off to a winning start at the Sportsground. Having a good home record is vital to us so the key thing is to channel all our excitement, effort, fight and desire to win at home into the process of winning the game."
Connacht: Shane Layden, Niyi Adeolokun, Darragh Leader, Dave McSharry, Danie Poolman, Jack Carty, Ian Porter; Denis Buckley, Dave Heffernan, Nathan White, Mick Kearney, Quinn Roux, John Muldoon (Capt), Jake Heenan, Eoin McKeon.
Replacements: Sean Henry, Finlay Bealham, Rodney Ah You, George Naoupu, Willie Faloon, Kieran Marmion, Miah Nikora, Conor Finn.
Simon Zebo makes a return to provincial action tonight as Munster take on Edinburgh at Thomond Park, kick-off 7.35pm.
Head coach Anthony Foley has named his side, which includes Emerging Ireland duo Andrew Conway and Ian Keatley in the starting XV, while their touring colleagues Dave Foley and Tommy O'Donnell are named in the replacements.
Hooker Kevin O'Byrne, back-row Shane Buckley and centre Andrew Smith all start, making their competitive Munster debuts.
Foley has made six changes to the side that lined out against London Irish in Waterford last week with BJ Botha returning to the front row while Shane Buckley takes the place of Robin Copeland at No. 8.
Johne Murphy, Andrew Smith and Ronan O'Mahony retain their places in the backline but make the positional switches with Smith and Murphy linking up in the centre partnership while O'Mahony moves to full-back.
Cian Bohane has undergone a scan during the week after sustaining a knee injury against London Irish, and has been ruled out of action for the immediate future.
Munster: Ronan O'Mahony; Andrew Conway, Johne Murphy, Andrew Smith, Simon Zebo; Ian Keatley, Duncan Williams; John Ryan, Kevin O'Byrne, BJ Botha; Donncha O'Callaghan (Capt), Billy Holland, CJ Stander, Sean Dougall, Shane Buckley.
Replacements: Duncan Casey, Alan Cotter, Stephen Archer, Dave Foley, Tommy O'Donnell, Cathal Sheridan, Johnny Holland, Ivan Dineen.