O'Brien finally makes his Leeds debut today - 17 years after being released by them.
The Harrogate-born centre-back, 31, has joined the Elland Road outfit on a one-month loan from Bolton.
Republic of Ireland international O'Brien, who has made close-on 500 career appearances with Bradford, Newcastle, Portsmouth and Wanderers, goes into boss Simon Grayson's starting line-up at Scunthorpe.
But he revealed: "Although I am delighted to be back, I would have been even happier if I had been given the chance of playing first-team football for Leeds all those years ago.
"But I got released at 14 without getting the chance to move up the ladder with Leeds.
"Paul Hart was the youth team coach and he put together an excellent team with the likes of Harry Kewell and Jonathan Woodgate.
"Competition was very high, and it was deemed too high for me. But it is ironic how, 17 years later, the wheel has turned full circle. I'm determined to make up for lost time."