The Gunners blew the race for a top-four Premier League finish wide open as first-half goals from Alexandre Lacazette and Laurent Koscielny closed Arsenal and Manchester United, who beat Brighton earlier in the day, to within three points of Chelsea in fourth.
“I’m extremely angry, very angry indeed. This defeat was due to our mentality more than anything else, our mental approach. We played against a team more determined than we were and I can’t accept that,” said Sarri, who spoke in his native Italian as he wished to send a message to his players.
“The fact is it appears this group of players is extremely difficult to motivate.”
On current form Sarri’s men look likely to be caught by Arsenal or United as a fourth defeat in 11 league matches underlined the need for the signing of Argentine striker Gonzalo Higuain on loan from Juventus, which is expected to be completed in the coming days.
Chelsea enjoyed 64 percent possession, but had just one shot on target to again question Sarri’s decision to start without a recognised striker with Eden Hazard’s impact limited in a central role, even against an Arsenal defence that had kept just one Premier League clean sheet since September.
However, Sarri insisted it was his players’ attitude and not his system that was the problem.
“I think when you see this kind of game, when one team is more determined than the other, you can’t really talk about tactics,” he added.
“From a technical point of view both teams are on the same level, but they were more determined. Tactics don’t come into it. Their high level of motivation was obvious throughout, particularly in both penalty areas.”
By contrast Arsenal boss Unai Emery’s selection was vindicated as Mesut Ozil was left on the bench for the full 90 minutes and a switch to a 4-4-2 allowed Lacazette and Pierre-Emerick Aubameyang to form a potent partnership up front.
Aubameyang should have opened the scoring after just five minutes when perfectly picked out by Lacazette’s low cross, but dragged his shot wide.
Kepa Arrizabalaga then produced a brilliant save to deny Koscielny from point-blank range, but it counted for little as from the resulting corner Arsenal took a deserved lead.
Lacazette did well to stay on his feet as he skipped past Marcos Alonso and Pedro Rodriguez before smashing the ball past Kepa at his near post.
However, Arsenal‘s defence remained vulnerable when put under pressure and Pedro could have levelled when his lob over Bernd Leno shaved the outside of the post.
Aubameyang came close again, this time in spectacular fashion with an overhead kick that flew inches wide with Kepa beaten.
Sead Kolasinac headed down Lucas Torreira’s free-kick into the path of Sokratis Papastathopoulos and his cross picked out the unmarked Koscielny.
The French defender mistimed his header, but the ball bounced in off his shoulder for his first goal since the Arsenal captain ruptured his Achilles in April.
Chelsea could have got a foothold in the game before half-time as David Luiz’s header came back off the post.
But in keeping with so many of their performances of late, Chelsea created little thereafter despite dominating possession.
Olivier Giroud was given a warm welcome back to the Emirates when he entered as a substitute, but even with the French international as a focal point, the visitors failed to threaten.
Sarri will hope Higuain, who scored 38 goals when the pair first worked together at Napoli in the 2015/16 season, is the answer.