TWO men have handed themselves in to police and have been arrested over an alleged assault on a train.

About 2.30pm today, police released images of the men on Facebook and Twitter, who they wanted to speak to about an assault on a 48-year-old footy fan. Police said the Facebook post went viral and reached 180,000 people.

“As a direct result of the Facebook post, a 26-year-old man attended Penrith Police Station at 4:30pm today where he was arrested by police,” police confirmed.

“His brother, aged 28, then contacted investigators at Sydney City Local Area Command before detectives attended his house in Zetland and arrested him.

“He was taken to Day Street Police Station and is also assisting with inquires.”

The two men were wanted for questioning over the alleged assault of a man while he was on the train home after attending the Penrith-Canterbury semi-final at Homebush on Saturday night.

Police say two men and two women boarded a train at Olympic Park Railway Station and became involved in an argument, during which time one of the men allegedly punched another 48-year-old man in the face several times.

Last night a man named Paul told 9NEWS that he was bashed after he noticed two men arguing with a woman and was worried it would turn violent.

“I thought I’d just ask the fellas to leave it alone and walk away, to just quieten everything down,” he said.

But one of the men starting throwing punches.

“One of them had a hold of me while the other hit me,” he said.

Paul was left with a broken nose, two black eyes and needed 24 stitches.

Paul managed to headbutt the attacker before the train pulled into Central and the men took off.

Police said they had CCTV footage of the offenders.

While Paul took a beating from the two men, he said he probably wouldn’t turn a blind eye if a similar situation arose again.

“You’d like to think if that was your daughter or your wife, somebody would do the same thing,” he said.