Emery admits losses to lesser lights will ruin top-four hopes
Unai Emery conceded that Arsenal cannot afford to lose against teams like Southampton if they are to finish in the top four of the Premier League this season.
A dramatic defeat on the south coast ended Arsenal's 22-match unbeaten run under Emery and the Arsenal head coach said the quality of their competition for next season's Champions League places means that they must be "very demanding" in these matches.
The loss, coupled with victories at the weekend for Chelsea and Tottenham Hotspur, leaves Arsenal three points adrift of the top four at the beginning of the busy festive schedule.
"The level is very high with the other teams and if we miss out on a win like today, we cannot be in the top four because the other teams are usually winning," Emery said.
"We need to carry on in our way, but it is not going to be easy to get into the top four.
"The other teams are playing at a high level and we need to be very, very demanding ourselves.
"After 22 matches without losing, we were still only fifth and that is because of the levels of the others."
Emery was forced to field another makeshift back four following suspensions to Sokratis and Shkodran Mustafi and an injury to Rob Holding.
Midfielder Granit Xhaka was selected on the left of a back three, while Hector Bellerin and Stephan Lichtsteiner left the field with injuries.
Bellerin, Emery said, is likely to be unavailable for "some weeks".
Asked if Arsenal may need to invest in new defenders in the January transfer window, Emery said: "I don't know. It's not easy. I don't believe a lot in this transfer window because it's not a very big possibility with the players.
Southampton manager Ralph Hasenhuttl joked that he would have to give free beers for season ticket holders for every home game after the club ended a sequence of 14 matches without a victory.
The Austrian sent free drinks vouchers to season ticket holders before this match, his first home game since replacing Mark Hughes.
Hasenhuttl added that the win marked the "first perfect step to help us", after celebrating with a lap of the pitch.
"It's amazing what the team can do in a week," he said. "It was very intensive, we had time to work on the basics and built the fundamentals for our game.
"I'm very proud of how focused and uncompromising they were, and when they had the chances how merciless they were."