Unprecedented demand for tickets for the Open at Royal Portrush, the first in Northern Ireland since 1951, has led to all four Championship days being completely sold out 11 months in advance.
It is estimated that around 190,000 fans will attend the tournament, which takes place from 18-21 July 2019.
Fans wishing to book their place at Royal Portrush next year still have time to visit TheOpen.com to purchase the remaining tickets for the four practice days taking place from 14-17 July.
A waiting list has been introduced for fans wishing to register their interest in purchasing any cancelled or returned tickets for Championship days which may become available at a later date.
Johnnie Cole-Hamilton, Executive Director – Championships at The R&A, said, "It is clear from the record-breaking ticket sales that golf fans are looking forward to the long-awaited return of The Open to Northern Ireland.
"We knew there would be great demand but it has been even higher than we expected and we expect fans will take advantage of the remaining practice day tickets now that we have sold out on Championship days.
"The 148th Open is set to be a truly historic and memorable occasion and we are encouraging fans to act quickly to avoid disappointment by securing their place at Royal Portrush through visiting TheOpen.com or one of our official ticket providers."
The R&A is also reminding fans of the importance of buying from only official sources of tickets.
Any tickets made available on secondary websites are done so without the permission of The R&A and as such, may be refused entry to the Championship.