Sunderland had almost twice as many shots on goal than United and that perseverance paid off in the 85th minute as John O'Shea steered the ball into the path of Demba Ba for the striker to put through his own net.
"In the second half, I think sheer pressure alone yielded the equalising goal and because of that pressure I feel it was deserved," O'Neill told safc.com.
"We got the break and we had time to go get the winning goal, it might have been harsh on Newcastle, but then again it's almost like a reversal from our game with them last year.
"The pleasing aspect was that even when time was running out we kept at it and applying pressure.
"The crowd were willing the ball into the back of the net.
"The noise that greeted the kick off was just fantastic and the noise that greeted the equalising goal was something I won't forget in a hurry!"