It was always going to be a hectic month for Mark Hughes, but January has just got a lot busier for the Manchester City manager.

Embarrassing. Humiliating, Mortifying. City’s exit from the FA Cup at the hands of Nottingham Forest was all of this and much more. Yet if there are any positives from a defeat that meant Hughes’s managerial career hit rock-bottom, it is that before the transfer window shuts he will be able to dispense with certain players who featured in a shambolic performance.

Hughes has more money to spend than any of his rivals in the Barclays Premier League, with Wayne Bridge’s £12 million arrival from Chelsea set to be followed by other new faces. But the City manager must also cast aside the clutter from within his dressing-room and ensure that heads roll if he is not to be forced out himself.

The 14 players whom he entrusted to do a job against struggling Coca-Cola Championship opponents let him down badly. With one or two exceptions, none emerged with any credit, although the performance of some players was more comical than others.

Dietmar Hamann’s curriculum vitae is packed with medals from across Europe, but the former Liverpool and Germany midfield player committed a schoolboy howler that allowed Joe Garner, the substitute, to seal victory after Robert Earnshaw had added to Nathan Tyson’s spectacular opening goal.

But an incident that occurred while the tie was goalless summed up best City’s farcical day. Forest had already spurned two great opportunities when they sliced open the home defence for a third time while City were down to ten men because Darius Vassell, set to be a replacement for the injured Shaun Wright-Phillips, was still off the pitch removing his earrings.

It was all too much for the City diehards, who booed their team off at the end of each half. “The reaction of the crowd was understandable,” Hughes, who fielded his strongest available side, said. “I can understand their frustration. The standard and the level of performance we have produced is not acceptable.

“But we have to make sure that this doesn’t become a regular thing. The individual errors obviously hurt us because they led to goals, but it was the performance I was more concerned about.”

While City supporters were left to reflect on a desperately bleak performance, Forest’s 6,000-strong travelling fans were anxious to make up for lost time. Despite winning promotion to the Championship in May after three seasons in League One, it has been years since the former European Cup winners have had anything significant to cheer about. But the team in 21st place in the second tier thoroughly deserved their moment in the spotlight.

Thanks mainly to Robinho, who was absent with a thigh problem, the City of Manchester Stadium has been the scene of some special goals this season, but the Brazil forward must have admired the way that Tyson set Forest on their way with a 25-yard volley.

This result was sweet revenge for John Pemberton, Forest’s caretaker manager. Hughes and Pemberton played in the Manchester United youth team together, but, while the former went on to establish himself as an Old Trafford legend, the latter’s career path took him to Rochdale and Crewe Alexandra before the pair ended up on opposite sides in the 1990 FA Cup Final.

A 25-year-old defender for Crystal Palace at the time, Pemberton was seven minutes away from receiving a winner’s medal when Hughes equalised, United going on to win the replay. “He stuck a knife into my heart that day,” Pemberton said.

With Billy Davies officially taking charge of Forest today, the caretaker manager returns to his duties as reserve-team coach at the City Ground and the first task for the man who succeeded where Arsène Wenger and Steve McClaren failed this season, in securing a win at the City of Manchester Stadium, is to pick a team for Forest’s reserve game away to Lincoln City on Wednesday.

Manchester City (4-4-2): J Hart 5 — P Zabaleta 4, M Richards 5, R Dunne 4, M Ball 4 — Elano 4, G Fernandes 3 (sub: D Hamann, 60min 1), V Kompany 6, S Wright-Phillips 5 (sub: D Vassell, 24 5) — F Caicedo 5 (sub: Jô, 70 4), D Sturridge 5. Substitutes not used: K Schmeichel, J Garrido, A Clayton, G Berti. Booked: Dunne.

Nottingham Forest (4-4-2): P Smith 8 — W Morgan 7, I Breckin 7, J Perch (sub: K Wilson, 17 7), L Chambers 7 — P Anderson 7, L McGugan 8, C Cohen 8, M Thornhill 7 — N Tyson 9 (sub: A Davies, 81), R Earnshaw 7 (sub: J Garner, 73). Substitutes not used: B Richardson, M Byrne, J Heath, J Reid.

Referee: L Probert Attendance: 31,869

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