Terrifying footage shows an amateur boxer being stabbed in the chest before fighting back to knock out the two attackers with his fists.

Jon Shaw, 34, was set upon by brothers Daniel and David Smith who barged into his gym and dragged him into the car park.

Footage of the attack, which was filmed by Jon's colleague, shows David grab him in a headlock while Daniel slashed at him with a blade.

Boxer and fitness instructor Jon was stabbed twice through the chest but despite his injuries, he managed to launch a fearsome fight back.

Video shows Jon taking on both brothers before landing punches which left them sprawled on the ground.

Jon managed to make his way to hospital where he was treated for a punctured lung after he was ambushed on June 1 last year.

Doctors told Jon that one of the stab wounds had narrowly missed an artery near his heart.

The dad-of-one, who runs DP Boxing Club in Worcester, declined to press charges but the pair were arrested days later, initially on suspicion of attempted murder.

Daniel Smith, 36, was ultimately jailed for 50 months after he admitted wounding with intent and possession of a blade and criminal damage.

His younger brother David, 34, received a 12-month community penalty for affray.

Speaking after the sentencing at Worcester Crown Court this week, Jon blasted the "soft sentences" handed out to the brothers."

He said: "I have my own reasons for not pressing charges but the whole attack was on CCTV. "

"You can't just stab someone up and get 50 months. He [Daniel Smith] nearly killed me he'll be out [of prison] next year."

Jon recalled the moment he was attacked by the brothers and revealed it was sparked by a Facebook feud.

He said: "I had posted a video on Facebook which included someone they both know and they wanted me to take it down but I refused."

"The day of the attack I walked into the gym and I knew there would be some kind of altercation but I expected it to be fists."

"When they ran at me I noticed the large red knife coming towards me and I just focused on that. When one of them got me in a head lock the other one stabbed me."

"I've been boxing for years and my training kicked in and I managed to wrestle myself free and chinned one of them and he went down."

"I got the other one down too and it was only then that I realised I'd been stabbed in the chest."

Shocking footage shows Jon's colleagues desperately trying to stop the frenzied attack.

At one point someone can be heard screaming: "Jon! Jon! Jon!" while another shouts: "He's got a knife!"

Despite his injuries, Jon trolled his attacked on social media by posting a video of the attack and dubbing the Smiths "the Chuckle Brothers"."

In the post which has racked up more than 24,000 views and shares, Jon wrote: "How to defend yourself against The Chuckle Brothers trying to end your life with a knife. "

"Imagine doubling up on a man and getting flattened. This shows the importance of self defence in today's society."

"As although there is no place for this, unfortunately it happens."

"When you put into context that this was over nothing more than a Facebook post, it makes you wonder where peoples' pride is."