Coach Stephen Kearney said Mannering, who is playing in his 14th season, will make a remarkable achievement reaching the 300 mark.
"If I look at the AFL as an example of that, over in Western Australia, I only know one player who's played 300 games for the Fremantle Dockers, [Matthew] Pavlich," Warriors coach Stephen Kearney said this week.
"My point is, it's a pretty significant achievement that he's had to deal with all of that too, and still knock out all of the tackles that he knocks out and the minutes that he plays."
Mannering will become the 34th player to reach the 300 mark when the Warriors face the Canberra Raiders on Friday.
He will be the 13th player to reach the mark having played all the games for just one club.
Nathan Hindmarsh (330 games), Geoff Gerard (325) and Andrew Ettingshausen (324) are the only players in the 300 club who failed to win a premiership, while John Morris (300) won one in his rookie season with the Knights but didn't play in the grand final.
The Warriors have a chance to give Mannering the perfect send off after booking their spot in the NRL playoffs last week, for the first time since 2011. That season Mannering was the skipper of the Warriors as they lost the grand final, his only appearance in the final.
According to the official Warriors website, Mannering has played in 140 wins, 156 defeats and three draws.
He's scored 63 tries, made 9,610 tackles and 28,725 total running metres. He also hasn't kicked the ball for the last four seasons.
A sell-out crowd is expected to be in attendance for Mannering's 300th, this morning there was less than a thousand tickets available.
