Celtic are currently on tour of Slovenia, and play their first pre-season friendly later this evening.
Brown has picked up a knock, and although his injury problem is not expected to be severe, the Bhoys did not want to task any risks with their captain.
Brown missed much of the back end of last campaign after picking up an injury, and Brendan Rodgers wants the Scotland international to be fully fit for the start of next campaign.
Brown was, therefore, forced to train on his own yesterday - as Celtic’s coaches put him through his paces.
Celtic are set to take on NK Celje in their first pre-season friendly later this evening, but Brown is set to miss out.
There were some doubts over Brown's future when Rodgers took over, but all the signs are that the midfielder is set to stay at Parkhead and play a key part.
Celtic are currently on tour of Slovenia, where they will play four pre-season matches before returning to Glasgow.
Celtic are then due to take part in the International Champions Cup, before they begin their quest to win their sixth Scottish Premiership title in succession.