“I am not fearful but that will be a subject that arises because of his contractual situation,” said Wenger, who equalled Sir Alex Ferguson’s record of 810 games managed in the Premier League.

“I can only repeat what I said until now.”

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• Relive Arsenal’s win at Crystal Palace

The best and worst of Arsenal on show

After three draws and just one win from their four previous Premier League outings, this was arguably an important game for the Gunners in their bid to remain in the hunt for a top-four finish, especially after wins for rivals Tottenham, Liverpool and Chelsea in midweek.

They started the day with six points fewer than they had at the same stage last season – and Wenger’s side ultimately finished outside the Champions League places – so a positive result and performance was needed to help ease any Arsenal fans’ concerns their campaign was in danger of fizzling out.

For large periods, the performance was certainly there. The visitors often produced some of their best attacking play of the season, particularly in the first half when Palace could not cope with short, intricate passing that time and again opened up the defence.

But their inability to finish off the many opportunities they created meant their opponents always had a chance to get back into the game. That proved the case early in the second half when Zaha’s cross caught Arsenal’s defence asleep and Townsend struck.

A five-minute spell of Arsenal disarray followed and the Gunners could easily have found themselves falling behind, but Sanchez – so often Arsenal’s saviour – settled the nerves with two moments of quality.

But even with a two-goal cushion Arsenal were never at ease, and Wenger’s concern about his side’s defensive frailties was highlighted by his decision to replace striker Lacazette with Francis Coquelin late on. That was still not enough to prevent Palace from reducing the deficit to one, setting up a tense finale.

“It was an excellent game, end to end, but you just cannot be convinced by Arsenal,” former Gunners and Crystal Palace defender Matt Upson, commentating on the game for BBC Radio 5 live, said.

“At times, some of their passing and movement was mesmerising, just brilliant – but at the other end you see their vulnerabilities and frailties and why they are sitting sixth in the league.”

Zaha shines again for resurgent Palace

It has been a strange old season for Crystal Palace.

They set an English football record by losing their first seven league games of the season without scoring a goal, but went into the Arsenal fixture unbeaten in eight matches – their longest such run in the top flight since 1990 and one which had moved them out of the relegation zone and into 16th.

The appointment of Roy Hodgson as manager has played a key role in that turnaround, but so too have the performances of Zaha.

The Ivory Coast forward has been in exceptional form since returning from injury in October and it was his trickery and intuition that allowed Palace to get back on level terms, jinking his way past Calum Chambers before crossing low behind a static defence for Townsend to slam home.

Only Jason Puncheon (32) and Chris Armstrong (31) have been involved in more Premier League goals for the Eagles than Zaha (30), underlining his importance to the team.

The ex-Manchester United player’s form has seen him linked with a move away in January and his departure would undoubtedly be a blow for Palace.

However, they showed in this game – and in recent displays – that they have enough quality elsewhere in their squad to be able continue their progress away from danger.

“At 1-1 I thought we were playing well and we were on the front foot, but the second goal was so difficult – to go down 2-1 was a difficult task,” Hodgson said.

“You have to give the players credit. At 3-1 a lot of teams would have capitulated, but we certainly didn’t do that.

“Our second goal was scant reward for the chances we had in the second half – but we were beaten by the better team on the day.”

Man of the match – Jack Wilshere

Gunners rule in London – the stats

• Arsenal have won more Premier League London derbies (120) than any other side.
• Roy Hodgson has won just one of his past 12 Premier League matches against the Gunners (D3 L8).
• Sanchez has had a hand in 13 goals in his past 15 Premier League London derbies (10 goals, three assists).
• Wilshere has now started four consecutive league games for Arsenal for the first time since March 2014.
• Crystal Palace have failed to keep a clean sheet in their last 10 league home games – their longest such run since May 2015 (15).
• Zaha has provided three assists in his past two Premier League games against Arsenal.
• Townsend both scored and assisted in a league game for just the third time – and for the first since April 2016 for Newcastle against Swansea.

What’s next?

It is another tough assignment for Palace as they host Premier League leaders Manchester City on Sunday (12:00 GMT kick-off). Arsenal, meanwhile, end 2017 with a trip to West Brom, also on Sunday (16:30).

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