Debutant Creighton made himself an instant hero with the Oxford fans
Oxford produced a dramatic comeback to beat York on the opening day with two goals in the last three minutes.
York had looked destined for victory after Richard Brodie fired home in the first half from a rebound when his initial shot had hit the post.
United were struggling until Matt Green lobbed Michael Ingham from Luke Foster's ball forward.
And, with U's fans still celebrating, debutant defender Michael Creighton crashed home a last-gasp winner.
Oxford manager Chris Wilder told BBC Oxford: "We can look back and there were a lot of below-par performances, but I always think the first day of the season is one to get out of the way with a win and we've done that and can move on.
"It's going to be bumpy ride and a rollercoaster. It's started like that and I fully expect it to continue."
York City boss Martin Foyle told BBC Radio York: "I thought we were excellent.
"We played some good football, there was quality in our play but we go back on the coach now with no points.
"There wasn't a player out there who was below par and I'm absolutely devastated for them."
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