O'Callaghan, fresh from his exploits at the weekend with Munster was last week named in the 22 for that game.
"Well I wouldn't exactly say I was 'fresh' after the game against Ulster. In fact I was quite tired really. It was a tough game, always is up there. Actually always is no matter where we play them."
But yeah it was a really tough game from start to finish. No let up. But in the end we came out with a win and that was great. The lads showed loads of commitment. Especially just before half-time."
"We were leading 8-0 at that stage but Ulster came a us in droves. There were white shirts screaming in right and left and fellas just had to put their bodies on the line. I can't remember the last time we won in Ravenhill."
"There was no let up but once we got over that and a period in the second half when they forced a line-out ten metres out - Trevor (Hogan) made a great steal on their throw - I think the sting went out of them. It's no small thing winning there so we were very pleased with the outcome."
"Not that we had much time to enjoy it. We had a quick bite to eat in the clubhouse and then Holl (Jerry Holland) had us on the bus to the airport for the flight home. The next day I headed off again for Dublin to join up with the Irish squad so it was a pretty hectic few days and I hit the bed pretty early Monday night".
And did he harbor hopes of making the starting line-up for Saturday's international?.
"Ah no, I didn't think so. I haven't had many games. I mean the one against Ulster was only the second game I started since last April or so. Paul and Malcolm are the guys in possession so the best I could hope for really is the chance to get on at some stage in the game".
And what about Ireland's chances of putting one over against the Springboks on Saturday?.
"Of course we can. Why not ? Like we beat Australia here this time two years ago and there was nothing really in it earlier this year when we played South Africa down there. It's going to be tough no doubt about that. "
"They are a massive side, better than earlier in the year. I don't think we will be looking at the game between them and Wales last week and using that as a yardstick. We'll be thinking of the games we played in the summer and how we felt after them, knowing that we could have done an awful lot better."