The American was 11 under playing the par-4 11th hole at Sheshan International Golf Club in Shanghai with a wedge in hand for his approach.
Playing from the rough and downwind, Finau's ball appeared on line and destined to bounce onto the green and within striking distance of the hole.
Instead, the ball landed on a sprinkler head and was catapulted about 20 metres over the green and into a hazard.
With his ball playable, Finau hacked his third shot back across in front of the green, from where he failed to get up and down and tapped in for a double bogey.
Despite his misfortune, Finau still clung to a one-shot lead over Patrick Reed at the time.
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