Hatem Abd Elhamed has tested positive for COVID-19 and will self-isolate for 13 days. .
The Israeli defender is currently isolating and will miss Celtic's match against Rangers on Saturday.
He reported feeling unwell after playing in his country's 2-1 Nations League defeat against the Czech Republic.
Countryman Nir Bitton had already tested positive for the coronavirus during the international break, and Abd Elhamed joins him in missing the crucial derby
Celtic boss Neil Lennon is now without a number of players as he aims to leapfrog Rangers at the top of the Premiership.
A club statement said: "Celtic Football Club can confirm that Hatem Elhamed has tested positive for COVID-19 while on international duty and is now required to enter a 13-day period of isolation in line with regulations in Israel.
"Our medical staff will maintain constant dialogue with him and will provide all required support. Everyone at the Club sends Hatem our best wishes and, of course, we hope he makes a full recovery as soon as possible.
"We are, of course, disappointed and frustrated that another player on international duty has tested positive - during an international period which is continuing to present huge challenges for the Club.
"During the remainder of this international period, as we have done throughout, we will be maintaining close contact with the relevant international associations, in order to ensure everything possible is being done with regards to the care and protection of our players, something which must be a priority.
"While FIFA regulations determine that clubs are obliged to release players for international duty, going forward we are sure wider discussions will take place around this hugely important issue. We will monitor these discussions closely."
Star striker Odsonne Edouard is currently isolating in France after testing positive for COVID-19. Although he's expected back in Glasgow one day prior to the match, concerns over his health and lack of sharpness mean he has to be considered a doubt.
Self-isolation has also ruled out Ryan Christie. Although the midfielder has not tested positive himself, he and Kieran Tierney were deemed 'close contacts' of Stuart Armstrong after the Southampton player tested positive.
An ankle injury means James Forrest is unavailable, while Albian Ajeti has not played since sustaining a hamstring injury against Hibs on September 27.
The Swiss striker is, however, expected to be fit enough for consideration on Saturday.
