After 21 holes the pair could not be separated, and with darkness descending at TPC Harding Park it was decided that the match would be put on hold.
McIlory had held the early advantage, with a birdie on the 1st seeing him move to 1 up, but Casey birdied the 4th, 5th and 7th to wrestle the ascendancy away from the world number one.
A birdie from McIlroy on the 10th reducded the deficit to one shot, but Casey held on to his lead – until the 17th that is. A timely McIlroy birdie at the penultimate hole pulled the match back to all square.
The Ulsterman had his chances to claim the victory, missing a 12-foot putt on the 18th hole and a 6-footer on the third extra hole, but neither player could engineer a win.
More to follow…