dunne
Paul Dunne of Ireland reacts after his birdie putt on the 15th hole during the third round at St. Andrews. Reuters

The first prize of 1.15 million pounds ($1.79 million) will be shared out among the professionals if an amateur wins the British Open later on Monday.

"Amateur players are not eligible to win prize money," the Royal and Ancient organisers said on their official Twitter account.

"Should an amateur win #TheOpen first-place money will be distributed proportionately among the professional players who have made the cut."

Irish amateur Paul Dunne leads the way on 12 under par alongside South African Louis Oosthuizen and Jason Day of Australia.

Dunne and Oosthuizen tee-off together in the day's final pairing at 1430 local time.

Day goes out with American Jordan Spieth (11 under), who is attempting to become the first player to win the year's first three majors since 1953, in the penultimate match at 1420.

American amateur Oliver Schniederjans has made the best start of the early competitors, dashing to 10 under for the tournament after a run of seven birdies in the first 10 holes.

Jordan Niebrugge, another American amateur, will also start his final round at nine under later on Monday.

($1 = 0.6429 pounds)

(By Tony Jimenez; Editing by Amlan Chakraborty)