Former footballer Paul Gascoigne "forcefully and sloppily" kissed a woman on the lips while drunk on a train, a court has heard.
The 52-year-old is accused of an "unpleasant" sex assault on the service from York to Newcastle in August 2018.
The ex-England star, who denies sexual assault by touching, told police he had "kissed a fat lass" to give her a "confidence boost", jurors were told.
The complainant was left "shocked and upset", Teesside Crown Court heard.
Opening the case for the prosecution, William Mousley QC said: "This case concerns a brief but unpleasant assault with sexual overtones on a train."
The jury heard that after his arrest, Mr Gascoigne, who now lives in Leicester, told police it was "a peck on the lips" and indicated he did not consider it a serious matter.
Confronted by passengers
Mr Mousley said the woman, who had been travelling home, noticed a "shouty and sweary" passenger behind her.
The prosecutor said that after drawing attention to himself, the man, whom the woman later learned was Mr Gascoigne, had tried to sit on her.
After the woman tried to move away from the former footballer, he put his hands on her cheeks and kissed her, the court heard.
When confronted by other passengers, the former Newcastle United, Tottenham Hotspur, Rangers, Middlesbrough and Everton midfielder told them he had tried to give her a "confidence boost", the court heard.
Mr Mousley added that, when questioned by police, the accused had tried to defend himself by saying other passengers had been teasing her about her build and that he had given her a "peck on the lips to reassure her".
Describing the alleged offence as a "blatant act", the prosecutor added that it was "humiliating" for the woman involved, adding: "Perhaps it was him showing off."
He added: "The prosecution case is this was a sexual assault and we will seek to prove it by making you sure that it was nothing else."
The complainant, giving evidence from behind a screen, told the jury the kiss was "forceful" and "not like a peck on the cheek".
She said she noticed Mr Gascoigne being "very noisy" on the train, adding: "There were lots of cans on the floor."
'I just froze'
She told the jury she had put on her headphones and tried to ignore the noise coming from Mr Gascoigne behind her.
"He kept saying sorry," she told the jury. "I said 'It's fine'. I was just looking out of the window.
"He said sorry a second time, and then tapped my arm.
"I turned around to face him and he grabbed my face and kissed me full on the lips, and I was taken aback because it was just completely out of the blue. I just completely froze."
Mr Gascoigne's barrister, Michelle Heeley QC, asked the woman, who cannot be named for legal reasons, whether a fellow passenger had said, following the kiss: "You've got a responsibility to other women on this train to do something [about the incident]."
The woman said: "I had already made up my mind to report it to the travel police, because it was unwanted behaviour, there was no instigation on my part of wanting any attention from him."
Concluding her evidence, she added any attempt by Mr Gascoigne to apologise was for only appearance, telling the court: "He was just saying sorry for the sake of it, not because it was actually meant."
A female passenger who was on the train told the jury that she saw Mr Gascoigne kiss the woman, saying that the alleged victim was "very shaken".
She told Teesside Crown Court that, moments after the incident, she had heard the former footballer say: "I was just trying to give her some confidence."
The witness said that earlier on in the journey she had seen Mr Gascoigne drinking something from a milk carton, saying: "It was not the colour of milk."
The trial, which is due to last five days, continues.