Arsenal vs Chelsea: Five things we learned as Alexandre Lacazette and Laurent Koscielny's first half double downs Blues

Arsenal 2-0 Chelsea: Alexandre Lacazette and Pierre-Emerick Aubameyang thrived together up top and Aaron Ramsey reaffirmed his value as Arsenal secured a vital three points in the top-four race

Arsenal secured a vital three points in the top-four race as first-half goals from Alexandre Lacazette and Laurent Koscielny guided the Gunners to a deserved 2-0 victory at the Emirates.

Arsenal started brightly, rushing the Blues’ defence into mistakes with a high-press and after 15 minutes Unai Emery’s side went ahead after Lacazette weaved through a scramble in the box and fired past Kepa Arrizabalaga.

Then, ten minutes before half-time, David Luiz’s reckless challenge on Aaron Ramsey gifted Arsenal a free-kick in the final third and Koscielny shouldered home from six yards.

Chelsea did threaten in brief spurts but stayed ingrained to the same pedestrian pattern of play as in recent weeks and rarely manager to endanger Bernd Leno’s goal until the closing stages.

And so, in the match touted as a battle between two managers in transition, it was the Arsenal boss who left with the greater imprint.

Here’s five things we learned from the game:

Aubameyang and Lacazette thrive together up top

When Pierre Emerick-Aubameyang and Alexandre Lacazette started together – to the delight of Arsenal fans – at the London Stadium last week, the Gunners produced one of their most listless performances of the season. The questions, still lingering from the Arsene Wenger era, as to whether the pair can ever function seamlessly together up top ramped to the next degree.

Yet, once situated ahead of a midfield diamond and allowed to play off one another like old fashioned forwards in a 4-4-2, the pair thrived alongside one another. Lacazette dropping slightly deeper, jostling and interplaying in the midfield while Aubameyang used all of his pace to run beyond Chelsea’s high-line – and should really have added to the Gunners’ total when one-on-one with Kepa in the first half.

Playing both can, at times, cost Emery’s side defensively, but here, going toe-to-toe against Chelsea in an open game, it was a well-construed gamble which gave the Gunners their tooth.

Ramsey reaffirms how badly he’ll be missed

With all the talk surrounding Mesut Ozil being on the bench prior to today’s kick-off, it was the inclusion of Aaron Ramsey which actually offered the biggest surprise in the Arsenal line-up. Usurping Alex Iwobi and pushed into a central attacking midfield role, it was the qualities which the Welshman offered - those that Ozil never could - that were so fruitfully apparent.

Tasked with harrying Chelsea’s defence, Ramsey’s high and physical press on Jorginho allowed Chelsea’s fulcrum no time to ponder idly in possession and in doing so dictated the intense pace of the game under which Arsenal’s fluid system thrived.

Ramsey offered the transition between attack and defence, the ability to turn tackles into quick-counters and, without his presence, you wonder how Arsenal could have commanded the game in such a fashion. Here he proved that he should be one of the first names on the teamsheet for Emery, only underlining how the decision to let him join Juventus looks ever more misguided.

Arsenal outfought Chelsea in the centre of the pitch (Action Images via Reuters)

Hazard stifled at false-nine again

Sarri was left with little option but to sink Eden Hazard in his ill-favoured false nine position with Gonzalo Higuain’s impending move from AC Milan yet to be forced through and Alvaro Morata seemingly on his way out of the club.

And, yet again, the Belgian’s brilliance was lost in a game where he wasn’t able to cast his influence. Hazard was forced to drop deeper to collect the ball in his desperation to get a foothold, but was then caught and squeezed out of possession on his heels by Arsenal’s pursuing defence. On the rare occasions that he was able to burst forward, he was latching onto direct passes which left little room for the jinking shuffles that make him such a menace to defenders.

For how long can Sarri afford to constrain the talents of the Premier League’s best player for the sake of his own Sarriball system, because when Hazard doesn’t fully fire, the team usually follows suit.

Luiz goes back to hairy ways

Unsung behind the brilliance of Eden Hazard, the days of David Luiz being likened to a ‘PlayStation footballer’ are long gone. Maturer – still disguised as a centre-back – the Brazilian is in fact one of the league’s most profitable playmakers – prior to today’s game the poodle-haired defender had made over double the number of accurate through balls than any other player in England’s top division. Against Newcastle last weekend, one such 70-yard no-look through ball to Pedro carved out Chelsea’s opener.

Yet today, the older, more erratic mix of creativity and chaos was on full display at the heart of Chelsea’s defence. In the opening minutes, an errant pass almost gifted Arsenal an open attack on goal, next he was cannoning a ball to Pedro overhead that almost sourced an identical goal, and then he was clattering into Aaron Ramsey in a reckless slide tackle for which he would be yellow carded and Arsenal would score their second goal.

The right time to tinker?

With 20 minutes remaining, Emery withdrew Ramsey and Lacazette – two of Arsenal’s outstanding performers – to a number of catcalls from the Emirates crowd. A neurotic tinkerer - in fact waiting to change his team for noticeably longer than usual - it’s hard to say the change benefited the Gunners, even if it didn’t in the end cost them.

Psychologically, the substitution acted in a way to confirm the manager was happy to try and tough out the win, for his team to drop deeper and not press with the same intensity.

What followed was 20 minutes of heightened pressure, with Chelsea having their most dominant period of the match. By blunting his attack, Emery invited pressure onto his team, forfeited his high-press and did seem to make the road to a well deserved victory slightly more strained.