Arsenal full-back Kieran Tierney may not be available for the remainder of the season and his manager Mikel Arteta could not even confirm whether he would be able to join up with the Scotland squad for Euro 2020 this summer.
Tierney limped out of Saturday's 3-0 defeat to Liverpool with what the club confirmed was ligament damage that will sideline him for up to six weeks. A statement on their website said that surgery will not be required though Arteta stopped short of even confirming that.
"We have to make sure first that he doesn't need surgery, which it doesn't look like it, and if that's the case the timeframe will be around [four to six weeks]," Arteta said. "It could have been worse because the action looked quite scary but he's feeling better and the damage is not that bad. At the end of the day it's not the bad news that maybe we were waiting for after the game.
"I don't know [if he will play again this season]. We're going to have to go day by day, see how Kieran is feeling, how the knee is reacting and when we get close to playing time and training with the team, depending on how he is feeling, we will make that decision."
Asked if Tierney would be available for the Euros, with Scotland's first major tournament since 1998 due to begin on June 14 against the Czech Republic, Arteta sounded a note of caution. "Again it will depend how things evolve in the next few weeks. Obviously he is so keen to play for us before the end of the season and he's extremely keen to represent his country in the Euros."
Even Arsenal's more conservative estimate of four weeks would rule Tierney, the club's only natural left-back, out of both legs of the Europa League quarter-final against Slavia Prague and likely at least the first leg of any semi-final.
Tierney's absence is a major challenge for Arteta to address not just because the decision to allow Sead Kolasinac and Ainsley Maitland-Niles to leave the club on loan in January left Arsenal with no other left-backs. Their only alternatives are moving right-back Cedric Soares to the opposite flank or redeploying Bukayo Saka, who got his first run of games in the senior side as a defender but has established himself as a vital component of the Gunners attack since.
Tierney is crucial to Arsenal's attacking play, he leads the team in chances created in the Premier League and Europa League with 33 in 31 games. His understanding with the likes of Emile Smith Rowe, Saka and Pierre-Emerick Aubameyang means that the Gunners disproportionately favor the left flank when building up attacks, with the 23-year-old's pace and whipped crosses vital attacking weapons.
"We're going to have to make some adjustments because his qualities are unique and we don't have anybody to replace these qualities within this squad unless we start to move a lot of pieces, which without any time to train is a little bit dangerous to do," Arteta said. "We're going to have to find different ways to fulfil that gap and use other things that can be as effective."
Asked whether moving Saka away from the right wing berth where he has excelled could create further difficulties for Arsenal in their build-up, Arteta added: "That's the reality. You have to change something. You have to find a different way of attacking.
"At the same time the structure when you are defending and in transition moments has to be stable and be done by players that are comfortable doing that. We knew that position was a weakness around the squad because we didn't have anybody to replace him. We have to find different solutions.
"We could not do anything in that [January] window [to bring in a backup for Tierney]. We decided to let Kolasinac out on loan as well, it's a decision we made."
Arteta refused to rule out a return to the three man defense he deployed earlier in his reign, espousing the value of flexibility even though Tierney was crucial to making that system work with powerful underlapping runs from the left side of the center back trio. However Arsenal line up against Slavia Prague it is hard to perceive them having quite the same balance they do with their Flying Scotsman in the side.
Arsenal will assess Martin Odegaard tomorrow to see if he can shake off an ankle issue in time to feature against Slavia Prague but Smith Rowe, Saka and Granit Xhaka are all available after missing Saturday's defeat to Liverpool.