Manager Neil Lennon says Celtic will make another bid for Finnish striker Teemu Pukki.
The 23-year-old, capped 24 times for his country, is currently with German side Schalke, who have turned down Celtic's initial offer.
"He is a player we like and we are trying to bring him in but it's not easy at this stage of the transfer window," revealed Lennon.
"Pukki is a very intelligent, good footballer."
Lennon, who also confirmed his interest in Iceland striker Alfred Finnbogason, watched Pukki in Finland's 2-0 friendly win over Slovenia on Wednesday.
The Celtic boss is keen to bolster his attacking options ahead of the Champions League play-off tie against Shakhter Karagandy, with the first leg to be played in Kazakhstan next Tuesday.
Interview - Celtic manager Neil Lennon
"We are very determined to bring players in and we're working very hard to do that," added Lennon.
"What we're looking for is value for money. While we do have money to spend, there is a limit for all players."
Gary Hooper, Celtic's top-scorer for the last three seasons, was sold on to Norwich
and Lennon sees similarities between Pukki and the departed Englishman.
"He's sharp, his movement is excellent, with a very good first touch - very similar to Hooper," he explained.
"I don't know if he'd weigh in with as many as Gary but he'd certainly get his fair share of goals.
"I'm not looking for a ready-made replacement because I think there is scope for Pukki to improve.
"He hasn't played much football at Schalke and certainly we'd give him the opportunity to play.
Lennon made it clear that goalkeeper Fraser Forster is not for sale
"[Chief executive] Peter [Lawwell] has worked very hard on this one and we're not giving up on it just yet."
Finnbogason, 24, has played 16 times for Iceland and has been heavily linked with a move to Glasgow this summer.
"Never say never," was Lennon's response when asked if Celtic would turn to the Heerenveen striker if a deal for Pukki could not be reached. "Perhaps we'll get both."
Newspapers have linked goalkeeper Fraser Forster with Benfica this week but Lennon was quick to dismiss those reports.
"There is absolutely nothing in that," he said.
"He's not for sale, he's far too important a player.
"We've sold three already [Hooper, Kelvin Wilson and Victor Wanyama] and we don't want to lose any more."