The unlucky Steven Mouyokolo is the victim. And the central defender has now returned to France to undergo an operation.
That is where the 26-year-old previously had treatment for the cruciate ligament damage he suffered while playing on loan for Sochaux.
Mouyokolo signed a year's deal after proving his fitness in two trial spells and an extensive medical.
He has played only two competitive games for the Hoops, but is considered a valuable addition to the squad and was registered in their 25 to play in the Champions League.
He is expected to be out for a considerable length of time, which is a huge blow to the player who has won so many admirers for the way he has bravely fought back from previous injury.
Lennon is also seeking medical updates on the men who are returning from international duty.
With the trip to play Hearts at Tynecastle at lunchtime on Saturday quickly followed by their Group H game in Italy against AC Milan, the Parkhead boss is anxious to discover who has come back with injuries.
His stars were on duty with their respective countries as far afield as Brazil, Nigeria, Kazakhstan, Ukraine, Russia and Mexico.
But it was the men who did not play who are giving Lennon most cause for concern.
Mikael Lustig looked certain to have to withdraw from the Swedish squad after being stretchered off at Tannadice.
The defender recovered in time to face the Republic of Ireland in Dublin last Friday, but, worryingly, he did not get any game time when the Swedes won in Kazakhstan on Tuesday.
James Forrest was ruled out of Gordon Strachan's plans for the game in Macedonia after picking up a knock while playing against Belgium on Friday.
Charlie Mulgrew and Scott Brown both played important roles - and the full 180 minutes - in Scotland's double-header against the Belgians and Macedonia.
But the midfield heroes had two very tough shifts in testing conditions, especially in Skopje.
Joe Ledley was removed from Wales' heavy defeat against Serbia, with 15 minutes of Tuesday's game remaining.
New signing, Teemu Pukki, is only now getting the chance to begin training with his team-mates, having had to rush away to play for Finland within hours of completing his deal from Schalke.
And the other late arrival, Nir Biton, is a doubt as he awaits his work permit. He was on the bench for Israel as they were held at home by Azerbaijan then again when they lost to Russia in St Petersburg.
If this document is not in place, the midfielder will not be able to make his debut this weekend.
Lennon will also check the condition of the clutch of under-21 players who have been away before he finalises his line-up for Saturday's game.