Callum Mills is a former AFL Rising Star, but the bottom has fallen out of the Swans defender's year after he broke his foot in an impromptu American football game with friends.
Mills and some Swans teammates were walking back from a cafe in Moore Park after training, throwing an American football between themselves, when Mills tripped and fell.
The Swans revealed on Thursday evening that scans had confirmed the 21-year-old had broken his foot and would miss the rest of the 2018 season.
"It was a really unfortunate accident and unfortunately Callum has an operation on Monday and will be out for the rest of the year — it's a bad break," Longmire said.
"It's something out of the blue and clearly very disappointing for him and us."
Mills has been replaced by rookie Ryley Stoddart in Sydney's team to play the Brisbane Lions at the Gabba on Saturday.
Taken by the Swans at pick three in the 2015 AFL draft, Mills became the first academy player from any club to win the AFL's Rising Star award when he streeted the field to take the prize after his first season in 2016.
He has played 55 games for Sydney and has been a lock in their defence for most of his two-plus seasons in the league.
