The £32million Brazilian started the day by telling a radio station in his home country he was leaving Eastlands and ended it with the goal to secure a place in the FA Cup fifth round.
Robinho had made little impact on a fiercely-fought cup tie in which Nigel Adkins' Coca-Cola Championship strugglers refused to give in to Roberto Mancini's millionaires.
Despite Martin Petrov's third minute opener the home side hit back to equalise through Paul Hayes - then Cliff Byrne created more anxious moments to reduce deficit after goals from Nedum Onuoha and Sylvinho.
Goodbye to all that? Robinho reacts after being substituted
Until his almost inevitable parting shot, Robinho's likely exit hadbeen an inauspicious one under a barrage of pressure from theChampionship side.
His only other mark on the game came in the third minute when hefollowed a flurry of step-overs by feeding Petrov on the left to crashthe opener past Joe Murphy.
That apart Robinho was relegated to the role of a virtual passengeras his side struggled to shrug off their persistent opponents amid awhite-hot atmosphere.
Game on: Battling Scunthorpe hit back through Cliff Byrne
If City's megastars thought Petrov's goal would take the sting outof their opponents they were sadly mistaken as Scunthorpe pressed insearch of an equaliser.
Martyn Woolford cut inside before firing a long-range effort acrossStuart Taylor's goal in the 10th minute, and five minutes later thehome side came even closer.
Paul Hayes played Marcus Williams into the left side of the box andonly a saving challenge by Abdi Ibrahim helped City shepherd the ballout for a corner.
Letting fly: Sylvinho unleashes a rasping drive to put City 3-1 up
Cliff Byrne got his head to McCann's corner only to see it hammerthe underside of the bar then bounce down for Vincent Kompany to bootclear. Hayes then screwed a shot on the rebound wide.
With chants of 'what a waste of money' greeting Robinho on the rareoccasion he touched the ball, the home fans were revelling in ahard-fought tie.
Petrov came close to a second in the 26th minute when he curled ashot from the opposite flank which was held well by the diving Murphy.
But he home side grabbed their richly deserved equaliser in the 29thminute when McCann's short corner led to confusion in the City box andHayes found space to volley into the top corner.
Jump to it: Nedum Onuoha prods home to restore City's lead
As confidence continued to flood through the home side Gary Hooperblazed over the bar while Robinho's similar attempt at the other endalmost cleared the stand and drew more jeers.
But City nudged back ahead in the final minute of a busy half whenStephen Ireland threaded a neat ball into the Scunthorpe box and Onuohashot home from a tight angle.
Sam Togwell had the first chance of the second half in the 54thminute when he was cued up by Hooper to hit a long-range shot whichTaylor did superbly to tip over the bar.
Parity restored: Scunthorpe United's Paul Hayes overpowers the City rearguard to fire a fine equaliser
The ever-dangerous Petrov lashed another left-foot effort just wideafter a neat lay-off from Robinho before Sylvinho effectively wrappedthe tie up in the 57th minute.
The Brazilian was fed the ball 35 yards from goal and unleashed astunning left-foot strike which beat the helpless Murphy and crashedinto the top corner of the net.
City almost grabbed a fourth in the 64th minute when Petrov's fierceshot was deflected out for a corner, from which keeper Murphy twiceblocked shots on the line.
Mob rule: City hail Martin Petrov after his stunning opener
But Scunthorpe found renewed hope in the 69th minute when McCannfloated in a corner from the right which dropped for captain Byrne tostab home from close range.
Terrace humour: Scunthorpe fans in full flow
The home side pushed for an equaliser but the final say just had tofall to Robinho, who was fed by Petrov before lifting the ball into theroof of the net.
The Brazilian was substituted almost immediately and made a point ofshaking hands with each member of the City bench with his brief careerat Eastlands seemingly over.
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