The midfielder scored a spectacular goal in Saturday's 1-1 draw with Inter Milan, but then had to limp off after turning an ankle.
Manager Neil Lennon feared he would have to rule out Commons from the first leg of their Champions League third-round qualifier against the Finnish champions.
But after intensive treatment, the Scotland international is making rapid progress and is now confident he will be available for tomorrow's crunch game.
Anthony Stokes also suffered an ankle injury against Inter, and was initially considered to have a better chance than Commons of recovering in time. But it now looks like Lennon will have the midfielder available with Stokes struggling to make the bench for a match in which defender Thomas Rogne believes patience can be the key to giving them a lead to take to Finland for next week's return leg.
The Norwegian is aware of the disappointments Celtic have suffered in European ties at this stage in previous seasons, and warned it would be folly to charge into this match in search of goals.
He said: "It depends how Helsinki go into this game. If they are really defensive-minded, we will need to be patient and try to break them down. You never know, though, they might really go for it.
"We will see what happens. But, of course, it's over two legs, and we have got a lot of time to score the goals we need to win the tie."
Rogne is hoping a massive Celtic support will push them on to victory, and help nullify the fitness advantage held by the Finns, who are halfway through their season and who won their previous Champions League qualifying tie 9-2 against Reykjavik.
He said: "We are at home and want to attack the game as we normally would.
"We want to play our own game. We never sit back and defend, even away from home.
"A clean sheet is massive for us, but we want to score a few goals as well."
Rogne is not dismissing the challenge Helsinki present, however.
"They are going to be fit and really up for it," he said after a team meeting to study the comprehensive dossier compiled on the Finns.
"It's a really big game for them as well.
"There is no talk of us disrespecting them. We know they are a really good side and that it is going to be tough."
Rogne is encouraged by the performance Celtic delivered in their final warm-up game against Inter, a match he sat out to ensure he is fully fit to play tomorrow.
He explained: "I played on the Saturday against Ajax then the Tuesday against Norwich, and, in the past, when I have played a lot of games, a few strains have shown up.
"So, I took a little rest at the weekend."
Rogne is desperate to get an injury-free run after two years of problems and said: "It has been frustrating, ever since I came here, really.
"But the last eight months has been better, and, hopefully, I can build on that.
"It's just a different style here. It's higher intensity in training and in games.
"So, as a young boy coming over from Norway, you need to adapt to that and, hopefully, I'm fully adapted now."
