Teenage defender Calum Chambers scored his first goal for the club as Arsenal broke Burnley’s dogged resistance with a 3-0 win to climb to fourth in the table.

The 19-year-old right-back set up Alexis Sanchez to head the Gunners’ opening goal in the 70th minute and then scrambled home their second before the Chilean star added another late on.

That lifted Arsene Wenger’s side into the Champions League positions for the first time since September – and the long-awaited return of Theo Walcott as a late substitute provided the icing on the cake.

With Burnley packing their midfield and hoping to find Marvin Sordell on the counter-attack, the onus was squarely on the home side to try and break the deadlock.

They created plenty of openings, with Danny Welbeck playing a one-two with Sanchez and advancing unchecked to hit a shot that beat Clarets goalkeeper Tom Heaton, but struck Kieran Trippier as he turned his back.

George Boyd, who had already been booked, was fortunate to escape further punishment when he appeared to handle Santi Cazorla’s corner, but the incident went unnoticed and Arsenal’s frustration grew.

Cazorla should have opened the scoring, blasting wide after a cross from the lively Alex-Oxlade-Chamberlain, while Sanchez might have had a hat-trick before half-time.

On two occasions, the former Barcelona star wriggled free and thumped in efforts that were kept out by Heaton, while his third curled just wide of the goal-frame.

At the other end, there was little for Wojciech Szczesny to do, although Mathieu Flamini had to race back to stifle a chance for Danny Ings after Scott Arfield had made the break.

The pattern continued during the early stages of the second half as Mikel Arteta blazed over and Oxlade-Chamberlain’s drive was deflected wide by Ings.

Arsenal seemed certain to score when a low cross from Chambers was pushed out into the path of Cazorla, only for Michael Duff to block the Spaniard’s shot on the line.

Inevitably, it was Sanchez who finally settled the nerves of the Emirates faithful with 20 minutes remaining, leaping between Duff and Trippier to head home Chambers’ cross.

And the right-back added Arsenal’s second goal following a corner two minutes later, pouncing from close range after Welbeck’s drive had been charged down.

With the points all but secured, Gunners fans welcomed back Walcott – making his first appearance since tearing his cruciate ligment in January – with a 10-minute run-out in place of Oxlade-Chamberlain.

Walcott might have marked his return with a goal, but his angled attempt was tipped onto the roof of the net by Heaton, while fellow substitute Lukas Podolski struck the post.

Instead, it was left to Sanchez to record his second double in successive weeks, collecting a Kieran Gibbs cross in injury time and firing home from close range.

Arsenal: Szczesny; Chambers, Mertesacker, Monreal, Gibbs; Arteta (Ramsey 63), Flamini; Sanchez, Oxlade-Chamberlain (Walcott 80), Cazorla; Welbeck (Podolski 80).