Scans on the knee he injured in last Saturday's game will indicate whether the hard working No 8 is out for four to six weeks - the best scenario - or sidelined until 2021.

"The best we can hope for is that Sam's injured the MCL (medial collateral ligament) and it doesn't require surgery. If that's the case we could have him back before the semi-finals,'' Ratz coach Jake Maurirere said.

"But if he's done the MCL and ACL (anterior cruciate ligament), well, he's gone for the year.''

Hartnett was assisted from the field midway through the second half of the Ratz 39-12 win over Barbarian Hogs last Saturday at Taree Rugby Park.

Maurirere described Harnett as 'irreplaceable.'

"He's our leader, both on and off the field,'' he said.

"The amount of work Sam gets through during a game is unbelievable, especially at the breakdown and around the ruck.''

Hartnett attended training on Tuesday night with his knee in a brace.

"He's obviously disappointed, but even so, he had a good talk to the boys,'' Maurirere said.

Hartnett's rugby nous will also be missed, especially with the Ratz fielding a number of players new to the game this season.

This was evident in last week's win over Barbarian Hogs. While the Ratz were dynamic in open play, they at times struggled with the more technical aspects of the game.

Hartnett captained the Ratz to the grand final last year where an understrength side was comfortably beaten by Forster Tuncurry at Tuncurry.

However, this season the Ratz loom as genuine contenders in a competition that has gone ahead without Forster, the club withdrawing due to concerns about COVID-19 restrictions and a lack of numbers.

The Lower North Coast competition was formed in 2008 and the Ratz have yet to celebrate a premiership win.

Manning had a 19-19 draw with Wauchope Thunder in the opening round before thumping the Barbarians last week.

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Second round results

Maurirere pointed out that even if Hartnett doesn't require surgery, he will spend the majority of the competition-proper watching on from the sidelines while he recovers from injury.

A six week break would see him return in week eight on August 29. This would be two games before the start of the semi-finals on September 19.

The Ratz head to Gloucester to play the Cockies on Saturday.

"Fingers crossed that it's good news for Sam,'' Maurirere said.

"But if it's not, then we'll have to move on.''