Celtic forward Kyogo Furuhashi will miss up to a month with a knee injury, manager Ange Postecoglou has confirmed.
The 26-year-old attacker was hurt in Japan's World Cup qualifying win over China on Tuesday.
Postecoglou says the prognosis initially is "three to four weeks" out, but added that Kyogo is "optimistic about working hard to get back".
Celtic are due to play seven matches domestically and in the Europa League between now and 3 October.
Postecoglou's side host Ross County on Saturday in the Scottish Premiership searching for just a third league win of the season, with a trip to Seville to face Real Betis to come on Thursday.
Kyogo is also likely to miss the visit of Bayer Leverkusen in the Europa League group stage on 30 September.
"It is disappointing for him because he has had a great start," added Postecoglou. "But it is part of football - these things will happen and we have just got to get on with it."
The Japanese forward has made an impressive start to his Celtic career, scoring seven goals in nine appearances since signing from Vissel Kobe in August.
Kyogo's absence leaves new signing Giorgos Giakoumakis and Albian Ajeti as Celtic's principle centre forward options after Odsonne Edouard's deadline departure for Crystal Palace, and Leigh Griffiths' loan move to Dundee.
Celtic's other new recruits Cameron Carter-Vickers, Jota, and Liam Scales are available to face County.
"[They're all at] different stages of preparation," Postecoglou said. "Out of all of them, I think Giorgos is a little bit further behind. He didn't really do a pre-season with the team.
"We'll probably be a bit more conservative with him. With Kyogo going down we're a bit light in that area so we've just got to be careful."