North Melbourne key defender Nathan Grima might still be available for the start of the AFL premiership season, despite injuring his knee on Friday night.

Coach Brad Scott had feared the 26-year-old backman was in serious trouble when team-mate Jack Ziebell fell across his left knee in the Kangaroos’ pre-season cup opener against Richmond at Etihad Stadium.

But scans on Saturday allayed slight fears that Grima had ruptured an anterior cruciate ligament (ACL).

They confirmed North Melbourne medical staff’s initial diagnosis of a high grade medial ligament strain, which the club said would sideline Grima for four to six weeks.

While that will wipe him out for the rest of the pre-season campaign, it gives Grima a chance to recover in time for North’s March 31 season-opener against Essendon.

Scott took a few positives from Friday night’s performances – a last-gasp win over Richmond and a thrashing from Hawthorn – but acknowledged there was plenty of room for improvement.

Among the good signs were a strong showing in attack against the Tigers by young key position player Robbie Tarrant, who has played just nine senior games in four injury-troubled years on the club’s list.

“He performed the way I thought he would, he’s had a really good pre-season … He’s starting to look like the key position player we drafted,” Scott said.

The coach was also buoyed by the performance of 20-year-old midfielder Ben Cunnington, who he said was benefitting from increased physical maturity in his third year at AFL level.

“He’s starting to look like a genuine AFL midfielder, so he was pleasing,” Scott said.

But, after the Kangaroos lost all their meetings with top-four opposition last year, Scott said Friday night’s 25-point loss to the Hawks showed a class gap remained.

“Where we finished last year (ninth) and where Hawthorn finished (third), that game was probably reflective of that, so we’ve still got some work to do.”

AAP scl/imc