Celtic midfielder Nir Bitton has returned a positive Covid test while on international duty with Israel.
It means the player is ruled out of the club’s Premiership clash with Rangers on Saturday.
The result comes four days after striker Odsonne Edouard tested positive while with the French under-21 side.
Ryan Christie is also self-isolating after he was deemed a close contact of Scotland teammate Stuart Armstrong, who tested positive.
Celtic said events during the international break “are very concerning and frustrating”.
The club said in a statement: “We send our sincere best wishes to Nir and any other players or staff affected within the Israel squad. We are in constant dialogue with Nir and look forward to him returning safely to the Celtic squad as soon as possible.
“Clearly, recent events during this international period are very concerning and frustrating.
“We have worked tirelessly to ensure a safe and secure working environment and since testing has begun our players and medical staff have done a brilliant job in very difficult circumstances.
“Although we will never be complacent, throughout our own club testing programme, our squad has returned around 2000 individual negative tests since the outbreak of the pandemic, with not one positive test.
“The current situation has presented huge challenges for all within football and wider society which we do not underestimate in any way.
“While we apportion no blame whatsoever to anyone, this is now a very difficult position for us and, clearly, for all other clubs. Like all other clubs, we must do all we can to protect our squad and limit the very clear and obvious risks to players.
“Under FIFA regulations, clubs are obliged to release players for international duty.
“We will be maintaining close contact with international associations in order to ensure everything possible is being done with regards to the care and protection of our players.
“The priority must be the safety of our players at all times.”