Arsenal seem to enjoy playing against opponents who field a back three. Notable scalps in recent history include Napoli, Liverpool, Galatasaray and Sunderland – while West Ham should have been added to the list last season had Arsenal not thrown away a 2-0 half-time lead to draw 3-3.

The reason why Arsenal tend to do well against a variant of this set-up is because invariably, by deploying an extra man at the back, their opponents are forced to cede the flanks, either by fielding a narrow midfield, or asking the wing-backs to push up, thus leaving space behind. In this case, against Arsenal on Saturday, Watford did both, and that allowed Arsenal’s quality of passing to come in to play as they ran out 3-1 winners.

The main beneficiary of that extra space was Alexis Sanchez, who started up front for Arsenal, but found, as the wing-backs pushed up to close the space in front, he could dart into the gaps to stretch the Watford back line. Time and again Alexis timed his movements to come in from the left-flank; and indeed, all three goals that Arsenal scored in a devastating first-half involved him exploiting the space on that side.

For the first goal, Alexis met Mesut Ozil’s chipped pass by angling his run from the left-side and, as he went to control the ball, was bundled to the ground by the right wing-back, Nordin Amrabat. Santi Cazorla was then able to convert the resulting penalty. For the second goal, Alexis both started and ended the move, firstly by dropping deep to get the ball thus allowing Arsenal to play out from the back, and then getting onto the end of a cross from Theo Walcott to bundle the ball in. He then turned provider for the third goal, once again holding the ball up on the left-flank, before sending an inch-perfect cross onto the head of Mesut Ozil to finish.

With Arsenal set to confirm the signing of Lucas Perez this week, this felt almost like the coming of age performance from Alexis as No 9 so it’ll be interesting to see how Arsene Wenger configures his system now that he has recruited another striker. By shifting Alexis back onto the wing, Arsenal’s attack becomes very top heavy, although he is capable of doubling-up as a secondary playmaker to bring balance to the side. In any case, a midfield behind him like the one used against Watford should provide enough technical security.

It also means that Wenger has to go back on his word when he said that by playing Alexis “on the flanks he uses a lot of energy by chasing back. I would like to use his energy sometimes a bit more efficiently by going behind the defenders as he is a good finisher.” A solution might be to string three central midfielders across the middle, like Barcelona do, though that seems unlikely.

Certainly, Arsenal could have done with such a configuration in the second-half at Watford as their opponents switched to a 4-4-2 and constantly bombarded down the flanks. The Arsenal wide players had trouble tracking back, leaving too much work for Granit Xhaka and Santi Cazorla to do in front of the back four. As a result, Arsenal invited lots of pressure in the second-half, and in the end, might have been relieved to have only conceded one goal.

That Arsenal raced to a three-goal lead, though, at half-time is testament to the way they shuffled the ball from side to side quickly to expose the space on the flanks. Arsene Wenger said before the game that it was important, playing against a 3-4-1-2, that “we use the width of the pitch well and combine very quickly to penetrate their defensive block.” The Gunners did that superbly, with Xhaka and Cazorla the technical base that allowed Arsenal to spring attacks quickly.

In particular, the Swiss summer signing was excellent, as he sprayed passes to either flank and looked to spring Alexis behind whenever possible. He took the controlling mantle away from Ozil, who was quieter than usual, as he endeavoured to find the killer space to be of the same influence. Still, that’s not to say he didn’t have an effect on the game as every pass he played seemed to be loaded with purpose, and certainly, looking back at the goals, you can see that he was actually involved in every one of them.

Indeed, one of the main questions before the game was how Ozil would react to Alexis’ movements now that the latter had changed positions (and to a lesser extent, how Watford’s congested centre would force him to find different spaces in the game). Last season, most of Ozil’s key passes came from the left hand-side and indeed, the partnership between the pair, trading one-twos in the left-channel, is key part of what makes Arsenal dynamic.

Against Watford, Ozil found he couldn’t really operate in those same spaces as Arsenal generally tended to have an overload on that side anyway. With Nacho Monreal pushing forward, and Alex Oxlade-Chamberlain hugging the left touchline, Arsenal often had a 3v2 – or even a 3v1 if Alexis was left untracked. Of course, that didn’t happen as Younes Kaboul tended to follow Alexis all the way anyway, and that created a gap in the centre. Ozil finally took advantage late in the first half when he burst into the box to head Arsenal’s third, but for the most part, he tended hang back, stationing himself towards the right-side of the pitch as Theo Walcott ran inside. Actually, Ozil doesn’t mind doing this because by playing from the right, it creates a natural angle for him to cross the ball – indeed; he tended to do this a lot towards the end of last season.

Here, he did this early, creating the foul for the penalty in the eighth minute by just hanging back a bit as Arsenal broke down the right, then crossing the ball as Alexis timed his run into the box. As the half wore on, he was more a facilitator with his movements, only at one point getting close to Alexis to trade one-twos. But it was the effect of his late running that caused the difference later in the game, first by having a hand in the counter-attack by running from deep for the second goal, letting the ball run across him before releasing it, and then driving into the box to score his goal.

Wenger said he wants more from Ozil in terms of goals and if the partnership with Alexis works, it will be this sort of understanding that decides it. Against Leicester Alexis lacked the same support and runners going beyond him when he vacated his position that he did versus Watford.

Indeed, that’s the caveat that I will choose to end this article with on Alexis’ and Arsenal’s on a whole performance against The Hornets. It’s a much welcome first win, but the way that Watford were set up was conducive to Arsenal’s own, allowing the Gunners to build up through the flanks as they prefer. Of course, the balance was much better in the middle with the double pivot of Xhaka and Cazorla controlling play but the trouble the team got into in the second-half left them crying out for a ball-winner – Wenger tried to see the game out by keep-ball.

Strong links going to Sanchez.

Much of it started at Cazorla.

Xhaka moved it well from deep. Good stuff!#AFC pic.twitter.com/pQroZSYyLz — 11tegen11 (@11tegen11) August 27, 2016

For Alexis, his performance draws parallels to when the last pretender to the striker crown, Danny Welbeck, produced his first good performance for the club, against Galatasaray – conveniently also against a back three. With the opponents deploying a narrow midfield, and the wing-backs pushing up, he found the space that he is more used to – on the flanks – freely available. As a consequence, he delivered a devastating hat-trick that should have been the making of him as Arsenal’s striker.

Instead, in later games, he’s found space harder to come by and as a result, has breathed more easily when deployed on the left-flank. That’s not to say Alexis will go the same way (or Welbeck for that matter, as he still has time as a centre-forward), but Arsenal’s first win still poses questions that need to be answered.