But after a dramatic 25-24 success maintained his side's 20-year unbeaten run in Cardiff and extended their remarkable sequence of wins to 10, he was happy to look ahead to the visit of Clive Woodward's men to Lansdowne Road.
"It's great to look forward to the England game and maybe do something very special," he said.
Ireland have been less than impressive in their last two matches against France and Wales but they have discovered how to win in tight situations and O'Sullivan is confident of being able to give England a run for their money.
"England are not going to roll into town expecting an easy ride and we certainly are not going to give them one," he said. "It's a one-off shot, winner takes all.
"We're in our own backyard and that's a good place for us to be. Historically, we respond well in that situation."