It’s now five final losses for O’Sullivan this season with one more event before the World Championships next month.
But O’Sullivan insists he doesn’t let results affect him too much as he bids to defend his crown.
“Results don’t make me confident, my game makes me confident,” he added.
“If my game is in good shape then I’ll feel confident whether I’ve won tournaments or not.
“If I find a bit of form then you never know but if this guy [Robertson] keeps playing the way he’s playing then I think he’ll probably be the man to beat.”