Danielle Robert Moore, 30, came to the aid of Tyler Lindsley moments after Lindsley had begun swinging punches at the victim over claims he owed him money.

Port Kembla Court heard Lindsley and the victim, who were known to each other, had initially had a short but amicable conversation after running into each other in Burelli Street on February 9.

The pair parted ways, however a moment later Lindsley's friend called the victim back to their group and said he owed Lindsley money.

The victim denied that, saying he had no money on him anyway, prompting Lindsley to punch the man in the back of the head without warning, despite being told by a female friend with him at the time that he'd gotten "the wrong guy".

Moore claimed it soon became apparent Lindsley was losing the fight, leading him to join in the melee.

He and Lindsley fled the scene when police arrived, with officers catching up with their group in MacCabe Park a short time later. Lindsley was found in possession of the victim's backpack and wallet and arrested on the spot.

Police were unaware of Moore's involvement in the assault and allowed him and the other members of the group to leave. However, Moore was arrested that evening in front of Wollongong Police Station.

Lindsley and Moore were charged with affray and assault causing actual bodily harm.

In court on Monday, Moore pleaded guilty to affray and the lesser charge of common assault, prompting police to drop the actual bodily harm charge.

He was placed on a two-year good behaviour bond owing to his limited criminal record.

Lindsley is already serving a six-month jail sentence over the attack.