Arsène Wenger unleashed a tirade at his Arsenal players on Thursday which startled some of them in its severity, as he sought to refocus minds following the club's Champions League humiliation at Milan.

The manager bolted shut the doors of the dressing room at the training ground before the squad's warm-down session to turn the air blue. Having repeatedly employed the carrot, this represented the use of a large stick and the players could not remember seeing him so incensed.

Wenger had been quiet in the dressing room at San Siro after the 4-0 last-16 first-leg defeat, which has all but pressed the club out of Europe's elite competition for another season. It was their heaviest loss in Europe. Wenger prefers to analyse matches with a cool head and not deliver assessments in the heat of the moment but, after the early-morning return to Luton airport and a little sleep, his anger had not abated.

He had given the players a taste of what was to come in his post-match press conference, when he was unusually critical of their efforts, describing the result and performance as a "disaster". "We were punished and deservedly so," he said. "I felt we were never in the game, we were very poor offensively and defensively. It was shocking to see how we were beaten everywhere."

Wenger has run the gamut of emotions during a turbulent season but the Milan reverse was too much to take. He must hope that his outpouring can galvanise the team ahead of Saturday's FA Cup fifth-round tie at Sunderland, when Arsenal's last hope of winning a first trophy since 2005 will be at stake. The priority, though, is to finish fourth in the Premier League and qualify for next season's Champions League.

Wenger is expected to be without Laurent Koscielny, after the defender injured a knee at San Siro, and Thierry Henry has said his goodbyes at the end of his loan spell from the New York Red Bulls. Wenger will make changes to his starting lineup at the Stadium of Light and he is considering whether to rest the captain, Robin van Persie.

The forward Gervinho is in line to return after the Africa Cup of Nations, where he missed the decisive penalty for Ivory Coast in their shoot-out defeat by Zambia in the final.

The mood in the Arsenal dressing room remained dark. "We're really disappointed," Mikel Arteta said. "You fight for fourth place to play in games like this. We were all waiting for a game like this, against a great team in a great stadium, but you go down 4-0 and it's a difficult one to take.

"We were counterattacked too many times, playing away from home. We can't allow that to happen, and that was the key. They scored three goals on counterattacks. It's very, very disappointing, it's difficult to take and we have to change our minds because we have another tough game on Saturday."