Double champions Munster will equal Toulouse's tournament mark of 10 semi-finals when they clash with ASM Clermont Auvergne at Stade de la Mosson in the opening semi-final on Saturday.
And it all started for the Irish club and O'Gara with a 21 points contribution from their No 10 to the team's 31-25 victory over Toulouse at Stade Chaban Delmas 13 years ago.
Since then there have been a further four contests against French clubs for club and player, as well as two showdowns with both English and Irish opposition.
Along the way O'Gara has crossed for tries in wins over Toulouse, Leinster and Saracens, as well as putting the boot in with 27 penalty goals, eight conversions and two drop goals.
He has twice accounted for all Munster's semi-final points, against Stade Francais Paris in 2001 and Toulouse in 2003, with it all adding up to 118 semi-final points at an average of 13 points per match.
The Ronan O'Gara semi-final record:
2000 v Toulouse - won - 21 points (1T, 2C, 4PG)
2001 v Stade Francais Paris - lost - 15 points (5PG)
2002 v Castres Olympique - won - 20 points (1C, 6PG)
2003 v Toulouse - lost 12 points - 2PG, 2DG)
2004 v London Wasps - lost - 9 points (3PG)
2006 v Leinster - won - 20 points (1T, 3C, 3PG)
2008 v Saracens - won - 13 points (1T, 1C, 2PG)
2009 v Leinster - lost - 6 points (2PG)
2010 v Biarritz Olympique - lost - 2 points (1C)
That first semi-final for Munster and O'Gara contained a host of players who made huge impacts on the European club rugby scene - both then and in the tournaments that followed. For the record, here are the teams who contested that match at Stade Chaban Delmas, Bordeaux, on 6 May, 2000.
Toulouse 25 Munster 31 - HT: 15-11 - Attendance: 28,000
Toulouse: S Ougier; E Ntamack, C Desbrosse, L Stensness, M Marfaing; A Penaud, J Cazalbou; C Califano, Y Bru, F Tournaire, F Pelous, F Belot [capt], D Lacroix, C Labit, S Dispagne
Try - J Cazalbou; Con - M Marfaing; Pens - M Marfaing (5), S Ougier
Munster: D Crotty; J Kelly, M Mullins, J Holland, A Horgan; R O'Gara, P Stringer; P Clohessy, K Wood, J Hayes, M Galwey [capt], J Langford, E Halvey, D Wallace, A Foley
Try - J Hayes, J Holland, R O'Gara; Cons - R O'Gara (2); Pens - R O'Gara (4)
Referee: Jim Fleming (Scotland)