Kyogo Furuhashi's unknown return date is a "real concern" for Celtic, according to journalist Pete O'Rourke.
The Japanese frontman hasn't played since suffering a hamstring problem at St Johnstone on Boxing Day, which has forced him to miss 12 games in all competitions.
What's the latest news involving Furuhashi?
He enjoyed a fine start to life in Scotland, scoring 16 goals and laying on five assists in his first 26 appearances for the Hoops, two of which came against Hibs in the League Cup final to help Celtic collect the first piece of silverware available this season.
But just 14 minutes into Celtic's trip to St Johnstone, the 27-year-old injured his hamstring, and hasn't played since.
Fortunately for the Glasgow giants, they haven't missed the striker too much, with the draw against Hibs on Sunday the first domestic game they've failed to win since Furuhashi got injured.
Therefore, they remain on course to win the domestic treble and will be hoping to move one step closer to regaining the Scottish Premiership title with victory over St Mirren tonight.
But Postecoglou recently provided a worrying update on Furuhashi's fitness by saying that he's "nowhere near" making a return to training and said that he won't put a timeframe on his comeback.
The likes of Daizen Maeda, Georgios Giakoumakis and Liel Abada have all stepped up in his absence, but O'Rourke didn't underplay how big of a blow his current situation is.
What did O'Rourke say about Furuhashi?
He told GIVEMESPORT: "It's a massive blow for Celtic, to not even have a timeline for when he might be able to return is a real concern for Celtic."
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Will Furuhashi play again this season?
At this current moment, it's almost impossible to predict whether the striker will be fit enough to pull on the famous green and white again before next season.
While Postecoglou did state that Furuhashi is doing everything in his power to recover, the fact he didn't put a time frame on the injury might suggest that he's in a race against time to be involved again this term.
Celtic have coped brilliant in his absence, despite their recent European exit, but at the business end of the campaign, they'll want as many quality players fit as possible, and Furuhashi firmly falls into that category.