Mikel Arteta admitted he saw the worst and best of Arsenal after they came from three goals down to snatch a 3-3 Premier League draw at West Ham.
The Champions League-chasing Hammers looked to be cruising towards a victory which would have seen them draw level with Chelsea in fourth after goals from Jesse Lingard, Jarrod Bowen and Tomas Soucek.
But own goals from Soucek and Craig Dawson hauled Arsenal, at times shambolic in the first half, back into the match and Alexandre Lacazette's late header earned the visitors a point.
Gunners boss Arteta said: "The first half an hour was really disappointing, we weren't at the races.
"We conceded a quality goal, but then we didn't win enough challenges, we didn't show urgency, and we conceded another two goals that were unacceptable.
"That keeps me awake. It has happened too many times too often. At this level you cannot do that because your opponents are too good.
"But in the second half we played some of the best I have seen us play. We got better and better, and looking at some of the chances we should have scored six or seven.
"We can't go from here to there. But for the rest of the match I am proud of the team and the courage we showed. That shows me how far we have come together."
Hammers boss David Moyes was criticised for his unadventurous selection at Manchester United last weekend, but against the Gunners he unleashed Lingard, Bowen, Said Benrahma and Michail Antonio.
And all four were involved as West Ham raced into a two-goal lead with only 17 minutes gone.
First Antonio played a one-two with Benrahma and reached the byline before cutting the ball back to Lingard, who took a touch on the edge of the area before arrowing a fierce drive beyond Bernd Leno.
Moments later West Ham doubled their lead when Lingard's quickly-taken free-kick caught Arsenal completely off guard, allowing Bowen to dart through on goal and finish past Leno.
It was a horror show from the Gunners defence, who had switched off for the free-kick, and from Leno who was beaten far too easily at his near post.
West Ham were three goals to the good after half an hour when Soucek turned Antonio's downward header home.
But Arsenal pulled one back when Lacazette tucked away a cross from Calum Chambers via a deflection off Soucek.
They halved the deficit on the hour when another dangerous ball from Chambers was turned into his own net by the unfortunate Dawson for his second own goal in a week.
The Hammers almost secured the points when Antonio slid in to thud Benrahma's low cross against the far post.
Instead Arsenal were celebrating an unlikely point when Nicolas Pepe teased a fine cross into the path of Lacazette, who thundered his header home.
Moyes said: "We played really well for about 30 minutes, about as well as we've played for a while, but unfortunately we have a goal away before half-time that changes the game a bit.
"But Arsenal played well and made it difficult in the second half. It's disappointing not to take three points but we've given Arsenal a game and challenged them until the end.
"What we've done is make sure we are keeping going. We want to go as long as we can and keep the dream alive."
