Defender Boogaard hyperextended his left knee, fractured his fibia and tore his calf late in Saturday's stirring win over Sydney FC after falling awkwardly.

The 31-year-old refused a stretcher and walked off the field but after seeing a specialist on Monday, the triple injury blow is likely to sideline him for two months.

The Jets admitted in a statement Boogaard faces an "uphill battle" to play again this season.

However, the ligaments in his knee are still stable with the club's physiotherapist Justin Dougherty calling it a best case scenario outcome.

Still, it is a major setback and means the Jets will be without two of their main men following Andrew Nabbout's transfer to Urawa Red Diamonds.

Striker Roy O'Donovan is also suspended for the next two matches.

Newcastle coach Ernie Merrick said he would give Boogaard every chance to prove his fitness but admitted it's an unlikely proposition.

"Nigel will be doing his upmost during the recovery and rehabilitation process," Merrick said.

"He's a tough character and an absolute professional when it comes to looking after his body.

"He's not one to make a song and dance about it but Nigel goes through a great deal to get himself on the park, in top condition week-to-week.

"In saying that, he will be hard-pressed to get back to full fitness before finals which is disappointing for Nigel given the way he's played all season.

"No doubt it's a big loss for us, he's a leader on and off the pitch but I believe we've got guys that can step in and do a job which we've seen right across the season."

Lachlan Jackson, 22, is the Jets' next best option to fill in for Boogaard at centre-back alongside Nikolai Topor-Stanley.

Australian Associated Press