Ruben Amorim's unexpected Manchester United decision sets up Athletic Bilbao selection dilemma

As the clock ticked down at the Vitality Stadium and Manchester United chased a goal against Bournemouth with the kind of intensity that shows they haven't entirely abandoned this Premier League season, Luke Shaw turned to Ruben Amorim and sought clarification on something.

Shaw was seeking out an explanation of where he was supposed to be playing after Amorim had thrown on 17-year-old striker Chido Obi in place of Noussair Mazraoui, a substitution that suggested a move to 4-4-2 but resulted in pieces of the jigsaw being moved around to fit Amorim's 3-4-2-1 shape.

After the 75th-minute change, Shaw initially moved to left wing-back and then back to centre-back. He was trying to get a handle on his role, but he could equally have been asking Amorim, 'What am I still doing on the pitch here?'

It wasn't in the plan for the 29-year-old to play 90 minutes on his first club start in 434 days, just as it hadn't been in the script for him to play 75 minutes against Lyon at Old Trafford. After that run out, he was given the day off entirely against Wolves.

That won't be possible this week. The last time Shaw completed 90 minutes for United was on February 1, 2024. The last time he did so for England was in the European Championship final and he was injured again soon after.

Having forced him to empty the tank and go into the red zone against Bournemouth, Amorim will almost certainly have to ask for more in Bilbao this week. He would have preferred for Shaw to play an hour or a little more against the Cherries, building his fitness up for a Europa League semi-final that is easily United's biggest game of the season so far.

Shaw will surely have to start again in San Mames, even if that might come with a risk, given his nightmare run of muscle injuries over the last two years. It is needs must for Amorim and United if they are to salvage any kind of silver lining from this season.

The injury to Diogo Dalot has added to complications in defence for Amorim. At Bournemouth he moved Mazraoui to right wing-back and kept Patrick Dorgu on the left and that is likely to be the pairing at San Mames on Thursday. Although Harry Amass has made his breakthrough recently, starting him in a game of this magnitude at this stage of the 18-year-old's career feels like a step too far.

With Mazraoui repurposed to replace Dalot, Amorim is short of centre-back options. Lisandro Martinez is out for the season, and while there is hope Matthijs de Ligt will return to training this week, the first leg of the semi-final is likely to come too soon for the Dutch defender, who has been absent for a month.

Victor Lindelof is the only alternative centre-back, with Jonny Evans in reserve. The veteran was on the bench at Bournemouth but last played on December 19 and isn't ready for a game of this magnitude. That leaves Amorim with limited options.

"It was not the plan to have 90 minutes but you need to win games," Amorim said of Shaw on Sunday. "And you could feel that he was overloaded in that part of the field.

"He’s really good on crosses, he’s really good in the final third decision, he has a lot of quality. When we are losing or drawing, you don’t think about the next game. You need to win. I was not focused on the next game."

Now, the United head coach will be laser-focused on the next game. United need to survive a cauldron in the Basque Country to return to Old Trafford with the tie in the balance. It's not difficult to envisage this team being blown away by the intensity of Athletic Bilbao, who will have had a week off to prepare for this game.

They have the once-in-a-lifetime opportunity to reach a final on home soil and, roared on by their brilliant support, they will take the game to United this week. Amorim will need players who are ready to stand up to that challenge.

At his best, Shaw is capable of doing just that, but if he is thrown straight in again on Thursday, it will be a real test of his fitness. United can't risk him breaking down again.

But he is the best option for that role in the team, and this is now do-or-die for the season. It's a selection decision that is likely to come down to Shaw, Amass or Lindelof, and by starting Shaw on Sunday, Amorim suggested he is the one who will be called on.