NIC NAITANUI says his "heart hurts" but the West Coast star has vowed to prevail after confirmation he will need a second knee reconstruction.

The 28-year-old was cruelly struck down by a ruptured ACL in his 'good' right knee on Sunday against Collingwood, only 15 games into his long-awaited comeback from his first reconstruction.

It was a shattering blow, especially with the Eagles in contention for an unexpected premiership.

COMMENT Is Nic Nat's playing future in doubt?

In an emotional Instagram post accompanied by the song River by Leon Bridges, Naitanui wished his late mother Atetha was with him for support as he comes to terms with the setback.

"Times like this I wish I had your shoulder to cry on all day or a massive hug to say it’ll all be ok," Naitanui wrote.

"Time to suck it up n soldier on.

"My heart hurts right now but if you know me there’s some poor soul confronting tougher trials and tribulations in the world.

"God gives His hardest battles, to His strongest soldiers #watchmeprevail"

The post had 17,000 views in two hours and messages of support flooded in from across the AFL world and from supporters.   

Speaking on Monday night, coach Adam Simpson backed Naitanui to return "better than ever".

"My heart goes out to him," Simpson told Channel Seven.

"He did make a difference for us for this part of the year but he'll go through the same process and he'll be back better than ever.

"I'm sure in the coming days and weeks it will sink in, the work in front of him.

"But he's not scared of hard work and the journey will continue."