CELTIC manager Neil Lennon, his assistant and 13 first-team players have been forced to self-isolate after a team mate tested positive on return from a training camp in Dubai.
It follows controversy over the timing of the trip, just two days before Scotland went into lockdown from already strict restrictions.
On Friday, the United Arab Emirates had 5,055 new cases, nearly double that of Scotland.
A picture showing Lurgan-born Lennon and club captain Scott Brown apparently drinking beer by the hotel poolside also sparked criticism.
Celtic FC today insisted it had received Scottish government approval for their mid-season trip, despite its purpose being questioned by first minister Nicola Sturgeon, who expressed concerns over whether they were following social-distancing rules.
Assistant manger John Kennedy admitted on Saturday that there had been some minor "slip-ups" but maintained the photograph had painted a "false picture".
Celtic's statement confirmed today defender Christopher Jullien had tested positive for Covid-19 and was self-isolating at home, wishing him "a speedy recovery".
"While all of the other members of the squad and backroom team have tested negative, we have been informed by the authorities that, having been deemed `close contacts', Celtic manager Neil Lennon, assistant John Kennedy and 13 first-team players will be required to self-isolate on a precautionary basis as required by the current regulations.
"The contacts were identified during the period from Wednesday last week, primarily around flight and team coach travel, during which time Celtic applied the same rigorous protocols used for pre-season training camps, Uefa match travel and for all domestic match arrangements in Scotland.
"These protocols have served us well in the past, as the club has not had one positive case in our own `bubble' until now.
"As we have already stated, Celtic’s decision to travel to Dubai for a training camp was for performance reasons.
"Whilst we were in Dubai, the announcements made on January 4 significantly changed the Covid landscape.
"The reality is that a case could well have occurred had the team remained in Scotland, as other cases have done in Scottish football and across UK sport in the past week."
The exemption for elite sports training means that if a team stays within its bubble athletes/players don't have to quarantine when they come back.
Tonight's home Scottish Premiership match with Hibernian is going ahead without a raft of first-team choices.
