But he was more concerned that his players had not stood up to the physical challenge of the Saints, particularly Shane Long, who scored the second and fourth goals at St Mary’s.

“Southampton made the game very physical and we lost too may challenges and that explains why we lost,” said Wenger.

“But we were unlucky with the decisions of the referee. The first goal was offside, the second a foul and the third was a goal kick.

“If you’re a bit below par and, on top of that, three goals go against you in the decisions it’s very difficult. But well done Southampton and we hope that in the next game we have this type of decisions.

“I smile but what can I do about it? I must say they were sharper than us in the challenges and we have to look at what we can master.

“We cannot master the decisions of the referee but our own behaviour we can – and on that front I believe Southampton looked stronger in the challenges and we lost too many. Long got away with a lot, but he was good.”

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Per Mertesacker looked slow as Long danced or barged past him on occasions, and to a neutral it appeared that Laurent Koscielny was simply outmuscled, first by Long and then Jose Fonte, for the second and third goals.

The upshot was that Arsenal missed the chance to move above Leicester City into first place in the Premier League.

That, in itself, was less of a concern to Wenger than his team’s below-par showing ahead of home matches against Bournemouth and Newcastle, which both look like must-wins if Arsenal are to remain serious title contenders.

“I said before the game that being one point behind or in front is not too important, it's the quality of our performance that counts and we were not good enough to win the game,” Wenger said.

“We have just to look at that. On the other side we have not to moan too much because we play again in 48 hours. There is only one way to respond.”

He denied that his team had been unable to take the pressure of being at the top.

“Personally I don't think the pressure got to us but there's no way to check that. I felt we were physically not at our best tonight.”

Southampton manager Ronald Koeman dismissed Wenger’s criticism of the referee, preferring to praise Long, who has been in the shadow of top scorer Graziano Pelle, who missed the match with a knee injury.

“If you lose 4-0 it's not about the referee,” he said.

“It's not my way to analyse a game. But Shane Long created big problems and was very dangerous. He attacked the spaces behind the Arsenal defenders. He's a different number nine than Graziano and that's important.”

Long is likely to keep his place in Monday’s match away to West Ham United.

“I don't think Graziano will be back for Monday but we know the qualities of Shane and he was one of the key players against Arsenal.”

So should Dutch-born Curacao defender Martina, signed from FC Twente in the summer and only in the team thanks to an groin injury to first-choice right back Cedric Soares.

“We didn't sign the player to score goals,” Koeman said. “But it was a great goal because it's not easy to score against a great keeper like [Petr] Cech.”