The look on Kieran Tierney’s face when he limped off the pitch just before half-time against Liverpool said it all.
When a player manages to walk off after an injury, it is normally a reassuring sight, but on this occasion that was not the case at all.
A player usually knows when he has done something serious and Tierney’s devastated reaction to his knee injury spoke volumes.
He may have managed to get to his feet and trudge off the pitch himself, but Arsenal’s left-back clearly felt he had done something serious while going in for a challenge on James Milner seconds before the interval.
The extent of the problem will become clear in the coming days, but both Arsenal and Scotland will be waiting with bated breath for the results of the scan that will follow.
"Kieran felt something in his knee and he was in pain," Mikel Arteta told reporters after the game. "It looks like he will be injured, but we don’t know for how long."
In the grand scheme of things for Arsenal, the result of Tierney's impending scan will be more important than the actual result against Liverpool.
Mikel Arteta may have publicly been refusing to accept defeat in the race for a European spot via the Premier League but, in reality, Arsenal’s race had been run well before they were comprehensively beaten by Jurgen Klopp’s champions on Saturday night.
After this 3-0 drubbing, surely even Arteta will have to admit that his side’s only chance of qualifying for continental competition next season rests on winning the Europa League?
And that is why a potentially serious injury for Tierney could be so crucial at this stage of the campaign.
The 23-year-old’s importance to this Arsenal team can’t be underestimated and the fact that Arteta has no natural cover for the former Celtic man makes the situation even worse.
Cedric Soares replaced him against Liverpool and will do a decent job on the left-hand side, but the Portugal international is naturally right-footed and can’t offer anything like the threat Tierney provides down that flank.
The fact that all three of Liverpool's goals came down his side on Saturday night was evidence of that, even if Soares himself wasn't directly to blame.
This, then, is a real problem for Arteta, who is now facing up to a season-defining Europa League quarter-final against Slavia Prague on Thursday night.
Arsenal head into that first leg sitting ninth in the Premier League, seven points off sixth and nine points adrift of the top four.
The league season has been a mess and although there has been genuine improvement since Boxing Day, the defeat against Liverpool was a clear indicator of how large the gulf in class is that exists between Arsenal and the league’s top sides.
The Reds were on another level, dominating from start to finish and leaving Arteta’s hapless side to feed off scraps all evening.
"Every defeat is different, but this one hurts deeply because of the image that we showed and the lack of clarity that we wanted to get out from the game," the manager admitted. "We need to apologise to our people, to our fans. This standard is nowhere near what we want.”
Indeed, Arsenal mustered just three shots against Liverpool, two of which were on target, and finished the game having had a mere 35 per cent share of possession.
Without Granit Xhaka, who was missing through illness, they had nobody to conduct the midfield and the absence of the injured Bukayo Saka and Emile Smith Rowe left them short of energy and quality in attack.
It's only when they are not there that you realise just how much Arsenal rely on their two young academy products to add some guile to an attack which is left almost bereft of quality in their absence.
"I don’t care who was missing; that is making excuses," a clearly furious Arteta stated. "The international [break] is an excuse too and I hate excuses.
"Liverpool were much better than us in every single department. And they fully deserved to win the match by a bigger margin.
"I am fully responsible for that. The rest, about one player [missing], two players, three players, is just making excuses."
Captain Pierre-Emerick Auabmeyang was a passenger again for Arsenal, after starting on the left side of the forward line, and while Nicolas Pepe did at least put in a shift on the opposite flank, the Ivory Coast international barely troubled Andy Robertson.
Liverpool – with Fabinho imperious in midfield – gave Arsenal a schooling and the only surprise was it took them until 64 minutes to make their dominance count, with Jota heading home Trent Alexander-Arnold’s superb cross.
Mohamed Salah added a second soon after for Klopp’s side before a poor pass out from the back by Gabriel gifted Liverpool a third, Jota again the man on target.
It was a horrible end to a horrible night for Arsenal.
They have been much-improved against the other members of the Premier League’s perceived 'Big Six' this season, but this was a stark reminder of just how off the pace they remain.
Attention will now start to turn to Europe when they will get a chance to respond to such a miserable domestic performance.
But first we must wait to hear the extent of Tierney’s injury, which has the potential to define the closing weeks of Arsenal’s season.