Looking ahead to December, Marsters said it was not the first time he has had an injury like this, but hearing "clicks" in the ankle had him concerned.
He did say he hopes to make a quick recovery and return to Carlton on November 20 to have a full run with the pupils.
The pupils and staff had all paid coins to take on Marsters in a shooting competition.
In the end, their collective score was 63 goals, just behind his personal tally of 66.
"The junior coach had the chance to win it but she choked under pressure," Marsters smiled.
The school also held a sausage sizzle, with all the money being raised going towards the teenager's American trip, where he will also attend a try-out camp in Florida in the hopes of earning a basketball scholarship to a college over there.
Marsters and his family have a long history with Carlton as his mother and siblings also attended the school.
When speaking to the children he impressed upon them the importance of doing well in the classroom using his own story of travelling down to Nelson to try and earn a spot on the Giants roster while having to repeat his final year of high school to bring up his academic standards.
The New Zealand U23s are away from December 1-23.