Top scorer Kyogo Furuhashi and captain Callum McGregor are nearing a return for Celtic ahead of Thursday's visit by Bayer Leverkusen.
Both have been missing through injury but could be given game time in the Europa League Group G game in Glasgow.
Summer signing Georgios Giakomakis could also make his debut after injury.
Manager Ange Postecoglu said: "I expect at least a couple of them to make an appearance at some point, whether that's Thursday or Sunday."
Celtic lost their opening group game 4-3 against Real Betis after squandering an early two-goal lead in Spain.
But Postecoglu vowed to pursue similar tactics against the side sitting second in the Bundesliga and who won their opening Europa League game 2-1 at home to Hungarian champions Ferencvaros.
"They are a quality opponent and we'll go out there with the same intention as we did against Betis away and that's to go at them and try to be aggressive and attacking," he said.
"Hopefully, with the crowd behind us, we can create something special."
Postecoglu was looking forward to his first taste of a home game in a European group stage and thinks it is also one "the fans and the squad are super excited about".
Celtic were held to a 1-1 draw at home to Dundee United in the Scottish Premiership on Sunday and have won only twice in their last seven outings.
However, their manager insisted that "preparations are good" despite "a pretty heavy schedule with a thin squad" and objected to the "condescending nature of questions" about the start his side have made to the season under his charge.
Team news
Furuhashi, who had scored seven times before picking up an injury on Japan duty and has missed the last five games, Scotland midfielder McGregor, who has been absent for the latest four, and former VVV-Venlo striker Giakomakis have all returned to training.
Postecoglou says there is zero chance all three will start and does not expect to make many changes to his starting XI, but they will be assessed ahead of kick-off with the aim of giving them much-needed game time at some point.
Midfielder James McCarthy has recovered from a knock picked up against United at the weekend, but full-back Josip Juranovic will be missing after sustaining a hamstring injury in Sunday's draw.
Two Scotland internationals - winger James Forrest and left-back Greg Taylor - are among those still sidelined.
What do we know about Bayer Leverkusen?
Leverkusen finished sixth in the Bundesliga last season, but under new head coach Gerardo Seoane, the 42-year-old former Grasshoppers defender who led Young Boys to three straight titles in his native Switzerland, they sit second, three points behind Bayern Munich, after six games.
They are unbeaten in their four away games this season, winning three, including the latest two.
Ivory coast centre-half Odilon Kossounou was their big summer signing from Club Bruges, but it is 18-year-old Germany midfielder Florian Wirtz who is their emerging star, scoring in his last five outings.
The latest, the only goal at home to Mainz, was set up by former Celtic right-back Jeremie Frimpong, while striker Patrik Schick, who scored a wonder strike for Czech Republic against Scotland at the summer's Euro finals, and winger Moussa Diaby, who found the net for Leverkusen against Rangers last year, add to the visiting goal threat.
What they said
Celtic manager Ange Postecoglou: "They have been a strong Bundesliga side for a number of years now and have a great pedigree.
"If you start looking for strengths, I think you'll find them everywhere."
Match stats
This will be the first meeting between the sides. Leverkusen will be the 10th German team Celtic have faced, while their four meetings with Scottish opponents to date have all been against Rangers (winning twice and losing once).
Celtic have won just four of their 24 matches against German sides, losing 15, all four wins coming at home, including last time out against RB Leipzig in this competition in 2018-19.
When Leverkusen last faced Scottish opponents in the Europa League, they defeated Rangers home and away in the last 16 in 2019-20 edition, winning 3-1 at Ibrox.
Celtic have lost 10 of their last 17 home matches in major European competition, winning seven, since drawing 3-3 with Manchester City in the Champions League in 2016-17. Their previous 10 such defeats were spread across 50 matches.
Leverkusen have won five of their last seven away matches in major European competition, although they did lose their latest - to Young Boys in the Europa League last 32 last season.