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 form the final against Northampton.
This weekend he lines out in the familiar number nine jersey, with Jimmy Gopperth outside him at ten 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 Rugby 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.
With Boss and Gopperth as the half back partners, the rest of the backline is the same as selected to start against Ulster.
Noel Reid (who in the end didn't play against Ulster) and Brendan Macken start in the centre, hoping to take their end of season B&I Cup form with them into the Guinness PRO12. 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.
Tickets for the first home game of the year next Saturday (Kick Off: 2.40pm) against the Scarlets in the Guinness PRO12 are still on sale at www.leinsterrugby.ie/tickets
Leinster
15. Zane Kirchner
14. Fergus McFadden
13. Brendan Macken
12. Noel Reid
11. Darragh Fanning
10. Jimmy Gopperth
9. Isaac Boss
1. Cian Healy
2. Sean Cronin
3. Mike Ross
4. Ben Marshall
5. Mike McCarthy
6. Dominic Ryan
7. Shane Jennings
8. Sean O'Brien CAPTAIN
16. Bryan Byrne
17. Jack McGrath
18. Tadhg Furlong
19. Tom Denton
20. Kevin McLaughlin
21. Luke McGrath
22. Ian Madigan
23. Mick McGrath
Referee: Nigel Owens (WRU, 112th competition game)
Assistant Referees: Neil Paterson, Bob Nevins (both SRU)
Citing Commissioner: Paul Minto (SRU)
TMO: Jim Yuille (SRU)
Guinness PRO12
Suite 208, Alexandra House,
The Sweepstakes
Ballsbridge, Dublin 4, Ireland