"Yesterday I had a bit of a sad moment but you have to snap back into reality," O'Gara said as he reflected on his departure.
"It's a special club. I attacked it at the start and thankfully a few of the boys got on board with my ideas and we grew but if we don't do the business [tonight] it doesn't count for anything."
Asked whether he had a message for supporters and the city in general, O'Gara, who has five children, said: "If the school is an example of the people of Christchurch, it was brilliant.
"They were so friendly and accommodating and warm. Obviously what happened earlier in the year ... the resilience of the people, the warmth of the people — great people, fantastic area. For me, I am young, I feel there will be a twist in it and I'll be back. In that regard I've given it my best shot and hopefully the boys will feel the same. It will be with a heavy heart that I leave."
O'Gara has given such value during his two years at the Crusaders alongside Robertson, and the pair have become so closely aligned, that it's not too difficult to imagine them both coaching the All Blacks at some stage and probably fairly soon.
Steve Hansen's successor won't be known until after the World Cup, and while O'Gara's departure as head coach of La Rochelle (a club Hansen played for) may make things a little more complicated in terms of Robertson's ascension to the top job, stranger things have happened. O'Gara presumably has a clause in his contract whereby a top international coaching offer takes precedence.
O'Gara has one final job to do in Christchurch and he can leave satisfied that he has done everything he can to bring title No 10 to the Crusaders. If they beat the Jaguares, Robertson will be the first coach to win three titles in a row, and given the issues in Christchurch this year and the closeness of the competition, that would be quite an achievement.