Practising Before a Nine-Hole Competition.

This is an interesting point and one which may be discussed for a time to come.

As an example, on a day when a 9-Hole Stableford is due to be played on Holes 1-9 of a golf course, a group of players wonder if they could play 18 Holes starting on the 10th Tee and then play in the 9-Hole Competition which states on the 1st Tee.

Under the 2019 Rules of Golf, Rule 5.2b, this is not allowed.

“Practising on the course” means playing a ball, or testing the surface of the putting green of any hole by rolling a ball or rubbing the surface.

And,

On the day of a stroke-play competition:

A player must not practise on the course before a round, except that the player may practise putting or chipping on or near his or her first teeing area and practise on any practice area.

The group would be deemed as practising on the course before a stroke Play Competition.

Note: This also applies to 9-hole Supplementary Scores.

The fact that the competition will only be run over Holes 1-9 is irrelevant because the course is the whole area within boundaries set by the Club or Committee.

If the designated 9 Holes are within those boundaries then any play on other holes within the same boundaries will be deemed as practising on the Competition Course.

See Definitions of Course and Round.

Course

The entire area of play within the edge of any boundaries set by the Committee:

All areas inside the boundary edge are in bounds and part of the course.
All areas outside the boundary edge are out of bounds and not part of the course.
The boundary edge extends both up above the ground and down below the ground.

The course is made up of the five defined areas of the course.

Round

18 or fewer holes played in the order set by the Committee.

There are three solutions to this scenario if the committee feel that several players may wish to play 18 Holes.

Allow the players to play the designated 9 Holes for the Competition first and then play the remaining 9 Holes.
If it is possible, through the design of the Golf Course, to geographically separate the 9 Holes designated for the Competition from from any other holes then the Committee could redefine the Boundaries of the Course, solely for that Competition. The remaining holes would therefore not be considered to be part of the Competition Course and so play before a Stroke Play Competition could be allowed. This would only be feasible on a course where holes not designated for the Competition did not run alongside or crossover any holes designated for the Competition.
A Committee, for a Competition, could adopt Model Local Rule 1-1.2. This Local Rule would modify Rule 5.2b and allow practising, on a Competition Course, before or between rounds. The Committee must ensure that it makes it clear to all players well in advance of the Competition that this Local Rule has been adopted, that it applies to all players and to which Competition it applies.

See Model Local Rule 1-1.2