The opening goal came from Olivier Giroud, after tapping the ball in following Mesut Ozil’s header after a swift counter-attack by the away side.
The second goal came from Alex Iwobi via a Jack Cork deflection. Arsenal had been in complete control in the second half. Kyle Naughton then scored an own goal off Sanchez’ cross, before Sanchez himself scored Arsenal’s fourth.
An even first half
The opening ten minutes of the game saw both sides looking smart in possession, but neither able to break down the opposition’s defence in the final third.
The first chance of the game fell to Naughton, who forced a good save from Petr Cech from 20 yards out, following some good play by Nathan Dyer.
Three minutes later, Wayne Routledge took the ball infield before teeing Gylfi Sigurdsson up from 20 yards but his shot flew just over the bar.
Arsenal’s first real chance fell to Sanchez, as his powerful shot from distance was well saved by Lukasz Fabianski at his near post.
A beautiful counter-attack resulted in the opening goal. Aaron Ramsey, Ozil and Iwobi combined to tee up Giroud who was inches away from scoring, the ball then fell to Sanchez, his cross found a wide open Ozil, his header bounced off Alfie Mawson into the path of a very grateful Giroud.
The goal saw Giroud become the first Arsenal player since Emmanuel Adebayor in 2008 to score in five successive games for the club.
One of Paul Clement’s main concerns will be how his side reacts to conceding the opening goal. During Bob Bradley’s reign, the Welsh side tended to look good when the scoreline was 0-0, but their heads would drop after conceding first.
He will be buoyed by Swansea ending the half well, and saw controversy as Ki Sung-Yeung was alleged to have been brought down in the box by Laurent Koscielny but referee Mike Jones booked the midfielder for simulation.
On the stroke of half time, Dyer intercepted a poor Gabriel pass, goes past Koscielny but rushed a shot from 20 yards that flew over, despite better options around him.
Second half belonged to the Gunners
Arsenal upped the intensity in the second half, with key players Sanchez and Ozil seeing more of the ball in advanced areas of the pitch.
Sanchez especially got more involved, and early in the second half got two half chances as Swansea lived precariously.
He then played a superb through ball to Ramsey to see the Welshman in on goal, his shot was saved well by Fabianski who rushed out of goal to stop the midfielder.
Arsenal were in complete control, as the Swansea defence was under siege the ball fell to Iwobi, his shot hit Cork and the ball inevitably looped over Fabianski in net.
The game seemed won by the hour mark, before Routledge saw a slap-shot from a difficult angle well saved by Cech.
Swansea kept getting chances though, Stephen Kingsley fizzed the ball into the box, as the ball ricocheted back to Federico Fernandez but the defender couldn’t find the target from 12 yards.
Arsenal’s third then went into the back of the net, and at this point you had to feel sorry for Swansea. They had numbers back in defence but Sanchez’ cross flew off Naughton at the near post past Fabianski.
The final nail in the coffin came when Sanchez scored Arsenal’s fourth. The Chilean volleyed home after some very smart play going forward by the away side.