Celtic boss Brendan Rodgers has revealed defender Alistair Johnston could miss the first two months of the new season following ankle surgery.
Canada right-back Johnston, a regular starter under former manager Ange Postecoglou after arriving from Montreal in January, initially sustained the injury in April.
The 24-year-old returned for last month’s Scottish Cup final win against Inverness, but has since failed to fully recover.
Rodgers, currently at a training camp in Portugal with his squad, said: “Alistair had an issue when he came back from international duty, a problem with his ankle.
“In the operation, he had a couple of bits removed, which was successful. He’s out here with us. It’s probably a six to eight-week injury, but hopefully he’ll be fit sooner than that.
“He’ll progress really well and better to have it done at this stage than some time during the season.”
Rodgers had better news on another Hoops defender, Cameron Carter-Vickers, who has rejoined the squad in Portugal ahead of schedule after undergoing knee surgery in April.
The USA centre-half had been expected to be out until the end of August, but could be fit in time for the season’s opener against Ross County.
“Cameron is doing very well, he’s out on the pitch,” Rodgers said. “After the surgery he had after the (Scottish Cup) semi-final he’s doing really well.
“He looks strong, so he’s progressing and he’s well on schedule to be back, so that’s good news.”
Rodgers, who returned as Celtic manager in May following Postecoglou’s departure to Tottenham, is hoping to further strengthen his squad.
Norwegian midfielder Odin Thiago Holm and Australia winger Marco Tilio were signed earlier this month from Valerenga and Melbourne City respectively.
Rodgers confirmed Tilio will not recover from an injury he sustained before arriving in Glasgow in time for the start of the season.
Following forward Jota’s recent departure to Saudi Arabian side Al-Ittihad, new forward recruits are high on Rodgers’ wish-list.
The former Leicester boss said: “The modern game, for a lot of players, it’s also a business for them. Careers are short and (Jota’s) been given an opportunity to go and look after himself and his family, so we have to respect that.
“So he’s gone and of course we have so many talented players here, but we’d like to do some business in that area of the team as well.”
Rodgers confirmed Republic of Ireland winger Mikey Johnston, hoping to force his way back into favour at Celtic Park after spending last season on loan with Portuguese side Guimaraes, will be sidelined for up to three months due to a back problem.
The Hoops are scheduled to play a second friendly against Portimonense in Portugal on Saturday before flying out to Japan, where they will face Yokohama F. Marinos (July 19) and Gamba Osaka (July 22).
Rodgers’ side are due to play Wolves at the Aviva Stadium in Dublin (July 29) and then Athletic Bilbao in their final pre-season friendly at Celtic Park on August 1.