In total, it was their 11th away loss of this disappointing league campaign, and left them five points behind fifth-place Chelsea.
The north London giants have now lost five consecutive away matches in the league for the first time since December 1984.
The Magpies then went ahead midway through the second half when, after Arsenal's defenders failed repeatedly to clear their lines, Perez helped the ball across the edge of the box to Ritchie, who fired past Petr Cech for his third goal in his last six league games. "We had 70 per cent of the ball, were 1-0 up and in the end you lose 2-1 and you wonder how you can lose this game", said a rueful Wenger.
Defeat on Tyneside means Newcastle have won on home turf against Arsenal for the first time in over a decade, and they were certainly good value for their win, as Benitez's side played with heart and flair.
Asked about Arsenal's wretched away form, Wenger said: "It's a lot about the head and sometimes there is no rationality in it". We conceded two goals from nowhere.
Willock, born in 1999, joins Ainsley Maitland-Niles, Reiss Nelson and Eddie Nketiah, all of whom are on the bench against the Magpies, in being the only Gunners players to have played for the club and been born after Wenger's first game in charge. Second half I feel some players paid a bit physically from having the game on Thursday night. "It's very hard to swallow".
With Atletico Madrid to face in the semi-finals of the Europa League, Wenger will have to tighten things up at the back.
His finish took Arsenal to a century of goals in all competitions this season, becoming the fourth Premier League club to achieve that feat after Manchester City, Liverpool and Spurs respectively. It has a subconscious weight in our minds.