Van de Beek running out of time
It had been 11 months since Donny van de Beek last started a game for Manchester United and even that was a dead rubber Champions League game against Young Boys. He had barely even been a peripheral figure for the last two years.
The appointment of Erik ten Hag was supposed to act as a fresh start for him, but injury has made life difficult in the early weeks of the season, so he was undoubtedly a surprise starter in Spain.
Seeing him play in the advanced role against Real Sociedad, with Bruno Fernandes on the right, felt like an audition to replace the suspended Portuguese playmaker at Aston Villa on Sunday.
READ MORE: United player ratings vs Real Sociedad
He had conditions to suit and finally make an impact here. He was playing in his best position, where Ten Hag believes he delivers his best performances, and had the backing of a manager he thrived under at Ajax. But he struggled to get on the ball and make any kind of contribution to the game.
If this was his chance to secure a place in the side, then it leaves Ten Hag with some questions to answer. Van de Beek's best contribution was out of possession, his marking job on Martin Zubimendi disrupting the hosts' build-up play, but if he is going to play as a No. 10, he needs to deliver more than that.
There will surely be more chances for Van de Beek and it is only fair to point out he is still building up his match fitness, but he is beginning to run out of chances to prove himself at this club.
De Gea's brilliance
When he uses his hands like this, David de Gea makes debates about how he uses his feet increasingly redundant. This was another good night for a United goalkeeper who looks to be in one of his hot spells.
It's only around two months since there were major question marks around De Gea's suitability for a Ten Hag team. In a sense, that discussion hasn't gone away, but as the Dutchman has been saying recently, the primary role of a goalkeeper is to stop the ball from going in the net and De Gea has been doing that rather well recently.
He was instrumental in keeping West Ham United scoreless at the weekend and when he was first called into serious action in San Sebastian he was faultless again. His initial save from Andoni Gorosabel was outstanding and the speed he showed to get across and deny Pablo Marin.
De Gea almost certainly won't be going to the World Cup with Spain due to the shortcomings that Luis Enrique sees with his feet, but on this form he's an undroppable goalkeeper for United.
A step too far
If United end up with a February play-off against Barcelona or Juventus when the Europa League draw is held next week, or a fixture pile-up that costs them points come the end of the season, then it isn't last night they will look back at, but the night they lost to Real Sociedad on September 8, or even the failure to score more than once against Omonia Nicosia at home.
Given this team had won by more than one goal away from home just once in their last 15 road trips - and that was in Moldova - winning by two against an accomplished side was always going to be a big ask. United went for it but they just didn't have the cutting edge in the final third to create enough, a familiar problem this season.
They are certainly a far better team than they were on matchday one of this competition when they lost at home to La Real. The improvement has been clear.
But they might now have to win a very difficult knockout tie to continue their European journey into March and, even if they manage that, it might only add up to fixture headaches later in the season.
Plan A, B and C
Ten Hag will receive some inevitable criticism for his second-half changes which seemed to unbalance United, although it felt like they had at least been planned.
The sight of Victor Lindelof being replaced by Scott McTominay clearly raised eyebrows, but Ten Hag has said he had a plan A, B and C to win this game by two goals and if this was the second of those, the third involved Harry Maguire playing up front.
The changes didn't make United a threat, but they hadn't really been a threat for a while. The idea they were in total control of this game in the first half felt like a stretch when they had scored from the only chance they created.
They struggled to get attacking players involved in the second half and even going long didn't drum up much of a threat until a frantic five minutes of injury time.
Ten Hag's changes didn't have the desired effect, but this was another night when United's lack of creativity was a concern.
Rashford's importance
The decision to rest Marcus Rashford on a night that carried plenty of meaning for United was arguably the biggest rotation gamble of Ten Hag's tenure to date.
Ever since the defeat to Real Sociedad at Old Trafford on September 8, Ten Hag has kept tinkering to a minimum, aware of the value of claiming top spot in the Europa League.
But with momentum building in the Premier League and Rashford becoming increasingly influential, Ten Hag felt he needed to rest his top scorer this season, especially as he only had recently recovered from a muscle injury.
There was always a chance he would be needed off the bench and so it proved in the second half, but Ten Hag will hope the trade-off was worth it come Villa Park on Sunday.
READ NEXT: