On the night he equalled former Manchester United manager Alex Ferguson’s record of overseeing 810 Premier League games, Wenger watched the brilliant Sanchez turn an exciting match with two superb second-half goals in the space of four minutes.
Shkodran Mustafi had given the dominant visitors a deserved lead after 25 minutes but Arsenal were made to rue a host of first-half near-misses as Palace roared back soon after the break with a well-worked Andros Townsend goal.
Then Sanchez, whose future at Arsenal remains uncertain, demonstrated his world-class talent, first with a thunderous 62nd minute snap shot and then a lovely piece of control and fine finish from Jack Wilshere’s long, precise through ball.
Despite James Tomkins ensuring a nervy finish with a late headed goal for Palace, the win left Arsenal still in sixth place in the league but they moved on to 37 points, alongside Tottenham Hotspur and to within a point of the top four.
Palace, beaten for the first time in nine games, are 16th on 18 points, just a point above the relegation zone.