A Good Samaritan stepped in and forced a man off a New York Subway train after he launched into a sickening rant and punched a woman in the face because she said he was 'manspreading'.

Sam Saia, 37, said she had politely asked the man to move his legs while she was sitting on the N train on Thursday, when he erupted into a violent rage, and began swearing at her, threatening her and punched her in the mouth.

Thankfully, a fellow straphanger intervened and grabbed the attacker, forcing him off at the next stop.

But Saia says she lives in fear of seeing the suspect again, who has not yet been arrested.

'That b*****d is still out there,' she told The New York Post on Friday after her commute home.

'I'm afraid he might retaliate. But I'm not going to back down.'

Brooklyn commuter Victor Conde, the brave passenger that rescued Saia, said he had intervened when he saw her in trouble and ordered her attacker to 'Get the 'F' off the train.'

'He was definitely not all there,' the 29-year-old added.

Video showed him shouting at the abuser: 'Get the f*** off the train. Get off the train bro, you just f***ing hit a lady.'

The unidentified good Samaritan is seen restraining the man and warning him that he better get off.

He said: 'You hit her in the face. She's bleeding. Look at her mouth. Just get off at the next stop.'

The incident began around 7:45 am on Thursday when Saia said she asked the man sitting next to her if he could give her a little more room.

He he ranted: 'B****, you ain't nothing! I've raped white b*****s like you, f***ing c---! You ain't nothing, you f***ing b----!' the man yelled, according to Saia.

A man, pictured left, is said to have punched a woman, pictured seated, after she asked him to move. A good Samaritan, pictured right, steps in

Sam Saia, 37, posted this picture on her Facebook page after the incident on the NYC subway where she says a man hit her after she told him to move

After Conde stepped in, the 'manspreader' tried to backtrack and apologize but no one on the train is having it.

It is assumed that he got off.

Speaking about the incident to Daily News, Ms Saia: 'This took me by surprise. It's just a matter of safety. I want my neighborhood to be safe. I don't want this to happen to other women or men.'

She added that she couldn't understand 'how you could do that to somebody.'

The video was posted on social media by fellow passenger Anthony Macca.

Mr Macca told Daily News that he did not witness Ms Saia get hit by the 'manspreader' but had heard the argument break out and started filming shortly after.

The good Samaritan, pictured right, tries to remove the 'manspreader', pictured left from the NYC subway car

The 'manspreader' turns to the woman, pictured seated, and is heard apologizing for hitting her