Provisional ball abandonment.

Question
I was playing a match play competition.My opponent sliced his drive to a par three and played a provisional to within 4 feet of the pin before finding his original ball.He played a very good down hill pitch to the green which struck his provisional stopping his original ball dead and cannoning his provisional off the green.He played his original and sank the putt for a three thus winning the hole against my four.Neither of us knew whether his provisional had become equipment and therefore automatic loss of the hole or whether it was rub of the green.We continued to play the match in good spirit which he won,either 3 and 2,or two up on the last. Unfortunately our Pro. was not around to clarify the position.You could not make it up but it happened!Can you clarify please to satisfy my curiosity. Michael.

Answer
Wow. Good question.  My first instinct is to call it a rub of the green, but since the ball is not in play I just don't know.  I haven't been able to research this very well, sorry. I'd try and ask a pro, or maybe email that one to the USGA since it's such an odd circumstance.

John