West Coast midfielder Andrew Gaff has been suspended for eight weeks for punching Andrew Brayshaw in the head during the western derby match between the Eagles and Fremantle on Sunday.

Key points: Gaff said he meant to hit his opponent in the chest to "get some space"

Gaff said he meant to hit his opponent in the chest to "get some space" The blow broke Brayshaw's jaw and dislodged three of his teeth

The blow broke Brayshaw's jaw and dislodged three of his teeth The suspension makes the West Coast star ineligible for the Brownlow Medal

The eight-week ban handed down by the AFL tribunal has ended Gaff's season and is the equal-longest suspension imposed this century — the other being the eight-match ban given to Fremantle's Dean Solomon in 2008.

Brayshaw, who at 18 is playing his first season of AFL after being drafted at pick two by the Dockers, is currently recovering at home with his parents after undergoing surgery on Sunday and will also miss the rest of the season.

The blow, which was delivered behind the play, left Brayshaw with a broken jaw and three dislodged teeth.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 34 seconds 1 m 34 s Western Derby chaos after Andrew Gaff punches Andrew Brayshaw

He will not be able to eat solid food for the next four weeks.

The tribunal was told Brayshaw's teeth were pushed two centimetres into the back of his mouth by Gaff's fist.

The hearing was told the displaced teeth may not be viable and may have to be replaced with implants.

Speaking to reporters after being handed the penalty, Gaff said he was disappointed in himself.

"The last 48 hours has probably been the toughest couple of days of my life," he said.

"People that I've spoken to and people that have seen me throughout that time know the world of pain I'm in, how much I'm suffering.

"I see myself as a caring, gentle and measured person, and that's why it's disappointing so much more.

"I'm disappointed for Andrew. I'm disappointed in myself.

"I'm disappointed for letting my team mates down. I'm disappointed for letting my supporters down as well."

Andrew Brayshaw thanked fans for their support in a post to social media after the incident. ( Instagram: Andy Brayshaw )

Gaff pleaded guilty to intentionally striking Brayshaw with severe impact to the head, one of the most serious charges a player can face within the AFL's disciplinary system.

He told tonight's hearing he asked to be interviewed on national television after the game so he could apologise to Brayshaw and his family, and had sent his opponent a text message later that night to say sorry.

"I feel sick that I hit Andrew," he told the tribunal.

"I feel so sorry for what has now happened to Andrew. I never intended for this to happen."

"Once I saw him lying on the ground, I instantly felt sick … mentally I didn't want to keep playing."

Andrew Gaff apologised for his actions immediately after the game. ( AAP: Richard Wainwright )

Gaff told the tribunal that before the incident, Brayshaw had bumped him repeatedly, and he meant to hit Brayshaw in the chest "just to get some space".

Before throwing the punch, 26-year-old Gaff had been widely regarded as one of the competition's fairest players.

He was having one of the best seasons of his career and was one of the favourites for the Brownlow Medal, but the hefty suspension means he is now ineligible.

There had also been ongoing speculation about whether the valuable midfielder would be lured home to Victoria at the end of the year, when he becomes a restricted free agent.

The AFL's lawyer Jeff Gleeson QC asked the tribunal to impose a suspension of eight to 12 weeks.

Andrew Brayshaw will be unable to eat solid food for four weeks after the punch from Gaff. ( AAP: Richard Wainwright )

"That is a significant penalty, it's an historically significant penalty, but this is an historically significant offence," Mr Gleeson said.

"Andrew Gaff looked at Brayshaw, squared himself and threw a punch," he said.

"The strike was unrestrained in nature, ferocious in impact and grave in its consequences.

"It was a full-blooded punch."

Gaff's lawyer David Grace QC told the tribunal a penalty of eight to 12 weeks would be "manifestly excessive", and asked the tribunal to take into account Gaff's good character.

"He's not the type of player that would have the intention of deliberately striking another player to the head," he said.

"He intended to punch him. He just didn't intend to punch him in the face."

Gaff was helped off the field after the incident. ( AAP: Richard Wainwright )

The eight-match ban handed to Gaff highlights the seriousness with which the tribunal now treats acts of on-field violence.

In 2008, Sydney's Barry Hall received the lesser penalty of a seven-match ban for his infamous full-blooded blow on West Coast's Brent Staker.

Last year Melbourne's Tom Bugg was suspended for six weeks for concussing Sydney's Callum Mills, while Richmond's Bachar Houli was rubbed out for four matches for striking Carlton's Jed Lamb, after the AFL appealed Houli's initial two-week punishment.

Interviewed on Channel Seven after the verdict, Brayshaw's father Mark, who is head of the AFL Coaches Association, described the incident as "a rotten bit of luck".

"Personally, I'm absolutely convinced that he intended to give him a good whack in the chest and for reasons that are now apparent, it ended up being on the mouth, and there's no interest whatsoever from our end in anything like legal or police proceedings," he said.

Andrew Brayshaw's brother Hamish plays alongside Gaff at the Eagles, and their brother Angus is a key midfielder at Melbourne.