If this proves to be Sven-Göran Eriksson’s swansong as Manchester City manager, then what a shame. Not only did they suffer an embarrassing defeat, but the Uefa Cup spot for fair play that was set to be theirs is now under threat because of the early dismissal of Richard Dunne, the captain, and there was also the sight of their supporters fighting with police. If Eriksson was hoping to make one last case for himself remaining in charge and changing the mind of Thaksin Shinawatra, the club’s owner, he should clear his desk and book a flight to Portugal for a third stint at Benfica.

While City’s travelling supporters left no one in any doubt as to where their loyalties lay, it seemed Eriksson’s players were less prepared to give a similar show of support. The manager’s leaving party turned into a humiliation in the Teesside fog and anything less appeared unlikely once Dunne had been shown the red card in the fourteenth minute for tripping Tuncay Sanli, conceding a penalty and leaving his defence in disarray.

Although Tuncay appeared to have lost control of the ball, Dunne was the last defender and Phil Dowd, the referee, had no choice but to send him off. Stewart Downing converted the penalty and Middlesbrough did not look back. Afonso Alves doubled the home team’s lead in the 37th minute after a powerful run from Fabio Rochemback before City capitulated in the second half, conceding two goals in as many minutes, first from Downing, who curled a sublime volley past Andreas Isaksson in the 58th minute, then Alves.

The rout continued at an alarming rate courtesy of Adam Johnson, Rochemback and Jérémie Aliadière before Alves completed his hat-trick to leave City in ruins, irrespective of the late consolation goal from Elano.

Eriksson has taken City forward this season, yet the fact remains that his time in charge will be stained by this defeat, a chastising experience the club may never forget. The Swede was due to hold talks with Thaksin and his representatives last night in the hope of agreeing compensation and he said: “You can say what you like about that game and I would have to agree. I have no excuses. After we went 3-0 down the players were somewhere else. This result is bad for everyone at the club, for the image of the club.

“I hope things will become clear very soon. I expect to speak to people, or them to speak to me at least, people in the club because I have not had an answer yet.” Middlesbrough have not scored eight goals in the top flight since 1950 and Gareth Southgate, the manager, was delighted to finish what has been a disappointing season on such a positive note.

“It was a mad day. We’ve not had much good fortune this season, so it all came in one day,” Southgate said. “The turning point was the sending-off and once we got the third goal it broke City’s spirit. Their circumstances weighed heavily on them and we showed ruthlessness in our finishing. If you’ve done the sort of job Sven has, then he can walk away with his head held high. It’s strange, but that’s what I told him before the game.”

Middlesbrough (4-4-2): M Schwarzer 7 – L Young 7 (sub: T McMahon, 75min), C Riggott 7, D Wheater 6, E Pogatetz 7 – G Boateng 7, F Rochemback 8, J Arca 7 (sub: A Johnson 62 7), S Downing 8 – Afonso Alves 9, Tuncay Sanli 7 (sub: J Aliadière 62 7). Substitutes not used: R Turnbull, A Taylor. Booked: Young, Pogatetz.

Manchester City (4-5-1): A Isaksson 7 – Sun Jihai 6, R Dunne 6, M Ball 5, J Garrido 5 – D Vassell 6 (sub: D Hamann, 62 6) , G Fernandes 6, S Ireland 5, V Corluka 5, M Petrov 5 (sub: Elano, 71) – Benjani Mwaruwari (sub: N Castillo, 12 6). Substitutes not used: J Hart, F Caçeido. Booked: Sun. Sent off: Dunne.

Referee: P Dowd
Attendance: 27,613

End-of-term report

Middlesbrough

Season’s summary: A period of underachievement.
How to improve: Wait for Afonso Alves to find his feet.
Player of season: Stewart Downing.

Manchester City

Season’s summary: Big step forward under Sven-Göran Eriksson.
How to improve: Retain the manager who has improved their fortunes. Oh . . .
Player of season: Richard Dunne.