Mikel Arteta admitted he knew Arsenal were in trouble against Brighton "from the first throw-in" of their 3-0 defeat.

The Gunners had made a perfect start to the season, winning all seven of their matches up to this point, but that came to a shuddering halt at the Amex Stadium.

Brighton were by far the better side, playing with a pace and intensity that Arsenal could not live with.

Arsenal struggled from almost the opening minute, looking ragged in their attempts to play through the Brighton press, and Arteta feared the worst immediately.

"From the first throw-in," Arteta said.

"You could sense it. It was so clear. We put ourselves in trouble, one time, two times, three times.

"We need to get out of that much quicker than that and that's one of the biggest lessons that we have to take from the game today."

Despite a first-half performance in which his side struggled to make any sort of impact on the match, Arteta opted against making changes at the break.

Asked if he was tempted to act at half-time and make a substitution, Arteta replied: "I was.

"But we believed it wasn't the right moment to do that with the things we wanted to change for the second half. That decision was made."

Arteta still praised the "remarkable" effort of his players in the opening weeks of the season, with 14 of the current squad having been at the World Cup over the summer.

However, the Spaniard admitted his side had been handed a "big lesson" by Brighton after dropping well below their usual standards.

"There were certain basics that you need to accomplish in football, especially in the Premier League, that we were very far from," Arteta said.

"In the first duel, the second balls, that put the game, especially how direct they were, in a really difficult place for us.

"On top of that, when we did regain the ball, especially in our own half, the amount of technical errors that we did... and we didn't respect any principles of play that you have to, to get out of man-to-man situations.

"That put us always on the back foot so it was very difficult to control the game.

"When we had moments of dominance and control, we opened them up, then we didn't finish those actions with the quality that is required to compensate all the other things that you have done.

"At the end of the day, they deserved to win the game and it's a big lesson for us."