Ex-Manchester United footballer Roy Keane flicked a 'V' sign and shouted aggressively after a taxi driver told him to smile, a court heard.
Keane, 43, had "stared aggressively" at taxi driver Fateh Kerar, 44, who made a "smile" gesture with his hands and drove off, Manchester Magistrates' Court heard.
But the former footballer followed him in his black 4x4 and caught up with the cabbie at a junction near traffic lights in Ashley Road, Altrincham, Cheshire.
Keane, who denies any wrongdoing, is alleged to have given a 'V' sign towards Mr Kerar then got out of his vehicle shouting and waving his arms about before getting back in his car and driving off.
Keane pleaded not guilty to the allegation, said to have happened around 11.15am on January 30 earlier this year.
The defendant, wearing a black suit, white shirt and blue tie, was asked to stand, give his date of birth and address, and entered his not guilty plea to causing harassment, alarm or distress to Mr Kerar - a Section 4A Public Order offence.
Mark Angus, opening the case for the prosecution, said: "Mr Kerar, a taxi driver by profession, picked up a fare, Miss Isman, driving to Hale village where she stopped to get some money.
"Mr Kerar saw Mr Keane in a black 4x4 vehicle.
"He described he had been staring aggressively towards Mr Kerar, at this point Mr Kerar gestured a smile with his hands.
"He drove off and Mr Keane follows behind.
"At a junction the defendant gave a 'V' sign towards Mr Kerar and then gets out of his vehicle, at this point he becomes aggressive, shouting and waving his arms around towards Mr Kerar and his passenger.
"He then gets back in his vehicle and drives away."
Keane sat listening intently, arms folded, sat behind the prosecutor with the courtroom packed with reporters as the case opened.