COLLINGWOOD veteran Nick Maxwell says that embattled teammate Marley Williams knows he has made a "massive mistake".

Williams' immediate playing future is unknown after the Albany District Court found him guilty of intentionally causing grievous bodily harm in an incident that occurred in Albany in December 2012.

Williams punched a man outside a nightclub on Boxing Day 2012, breaking the victim's jaw. The charge carries a maximum penalty of 10 years in jail. 

The 20-year-old will be sentenced on April 22 and Maxwell says Williams is well aware of what he has done and the seriousness of the situation that he currently finds himself in. 

"He put himself in a situation that he's going to regret for the rest of his life," Maxwell told radio station SEN. 

"But he chose to put himself in that situation and he knows that he made a massive mistake. But he's also a 20-year-old who made one mistake. He did the wrong thing."

Williams, who has played 22 matches after making his debut in 2012, is continuing to train with the Magpies but has made himself unavailable for selection until his future is determined.

Last Friday, West Coast rookie Murray Newman was sentenced to one year in jail for assault occasioning grievous bodily harm after being found guilty of fracturing a man's jaw at a Perth nightclub in November 2012. 

Maxwell says he has not discussed Newman's situation with Williams but believes his teammate would have been affected by it.

"I assume it would have," Maxwell said. 

"I haven't spoken to him specifically about that because we're trying to give him time to get his head right as well. He made the decision to take himself out of football because he doesn't feel he's in the right frame of mind to be able to actually go out there and perform." 

Maxwell, who was club captain when the incident occurred, says he has seen a transformation in Williams. 

"I've seen a change in him in the last 12 or 18 months," Maxwell said. 

"He's had to mature pretty quickly. 

"The commitment that he has made to his football and his professionalism, the way that he came back for his pre-season, he came back with the lowest skinfolds he's ever had in his career and ran his personal best time on day one in the 2km. 

"Also the work he's been doing with the (Salvation Army) over the last 18 months has just shown that he's a completely different person."