Richmond young gun Sydney Stack will spend Christmas and the start of 2021 in prison after his alleged COVID-19 breach.

The 20-year old was allegedly caught in the Perth party district of Northbridge in the early hours of Saturday morning.

He had been allowed to enter WA on compassionate grounds to attend his grandfather's funeral but told he must quarantine for two weeks at Northam, a town northeast of Perth.

However, police allege that he left the property and visited the entertainment precinct of Northbridge, where he was allegedly found.

Stack's bail application was refused on Saturday and he will now restart is 14-day isolation period in Hakea Prison. His case has been adjourned until January 6.

The youngster's manager Paul Peos said he is "very distressed and very upset".

"It's been very difficult to have communication and we're very disappointed but we'll continue to try and engage with him as best we can," Peos told reporters.

"He's having a very difficult time but it's the consequences of the times we're in, these are the charges and this is what he has to do.

"He did not sound OK, he sounded very distressed and very upset."

It marked the second COVID-19 breach by Stack, who was suspended for 10 matches and fined $100,000 for breaching AFL COVID-19 protocols with teammate Callum Coleman-Jonesย in September.

Stack has played 26 AFL games in 2019 after making his debut in 2019.