Co-incidentally when he arrived at his downtown hotel to check in, he was doing so alongside the Australian compromise rules team, here for the second leg of their series against Ireland on Friday night.
Both big games will be played at the 55,000 capacity Telstra Dome on successive days - and both games are sell outs, with Irish supporters accounting for at least half of the spectators.
The Ireland management has postponed until Thursday the scheduled announcement of the Ireland team to play Australia but O'Sullivan said there were no real dramas for the change in policy.
We had a bruising encounter against Argentina on Sunday." he explained. "There were a lot of sore bodies and guys who were carrying knocks and bruises so we decided to hold back for a day or two."
With the obvious exception of Alan Quinlan he anticipated all the squad would be available for selection.
That includes newly arrived Wallace, whom the Irish coach outlined has come with five games under his belt. We did not go down the road of having a shadow squad on stand by in Australia. We preferred the notion of people back home playing matches in the Celtic League and in Wallace's case it is better to arrive jet-lagged than ring rusty.
Wallace was welcomed into the fold with a round of applause and some leg-pulling, not least from Quinlan, the man he replaces, who said: I believe you had your bags packed by half time in the Argentinean match!.
Wallace said: Of course it was disappointing to be left out in the first place, but I'm here now and looking forward to being involved.