The goal heroes from the victory over Barcelona, Victor Wanyama and Tony Watt, have joined Gary Hooper and James Forrest in a race against time to be fit for the tie which could clinch the Hoops place in the last 16.
Watt, left, injured an ankle within minutes of coming on against St Johnstone at the weekend. After treatment, the 18-year-old managed to play on and even bundled home Celtic's goal.
But Watt was then forced to call off from the Scotland Under-21 squad to allow him to receive further treatment at Lennoxtown. However, it has become clear he is almost certainly out of Saturday's SPL game at Aberdeen – in which Celtic could go back to the top of the table.
And, unless his recovery rate increases over the next few days, Tuesday's game in Lisbon could also come too soon for the teenage scoring sensation.
With manager Neil Lennon revealing in SportTimes on Monday that there is a serious possibility Hooper and Forrest's hamstring injuries could rule them out of the game in the Stadium of Light, losing the potent threat of Watt would be another massive blow.
Lassad Nouioui has returned to training after being sidelined with a groin problem, and he could now be fast-tracked back to the starting line-up for Pittodrie.
Miku – taken off at half-time to make way for Watt in the draw with St Johnstone – did not travel to Miami for Venezuela's friendly with Nigeria and the loan striker will also come into contention.
Wanyama was another player to miss out on international action this week after informing the Kenyan management team he was not well enough to endure the 10,000-mile round trip to face Tanzania.
But it was not all good news because Wanyma revealed he might not be fit to resume training until Monday – the day Celtic head to Lisbon.
The 21-year-old said: "I contracted a throat infection after our match against Barcelona so I could not travel to Kenya.
"I'm recuperating well under the team doctor and will be back in training either tomorrow or Monday." Wanyama also told reporters in his homeland that he is ignoring speculation he is the target for both Manchester United and Manchester City.
He said: "I have also heard of the sentiments just like you. But let's see how everything will turn out. For now my focus is on my team, Celtic, as we wait for January, when I will be coming home for a week."