Brennan Cox will undergo surgery on a high-grade hamstring injury on Tuesday as he prepares to spend at least the next three months on the sidelines, according to High Performance Manager Phil Merriman.

Cox sustained the injury in the final quarter of Fremantle’s round one win over Brisbane after landing awkwardly in a marking contest with Harris Andrews of the Lions.

Meanwhile, Merriman says further specialist advice is required on the knee injury of fellow key defender Oscar McDonald – who is expected to be sidelined for an extended period.

McDonald’s injury came in the third term as he landed after a successful spoil on Brisbane’s Eric Hipwood.

“Brennan has gone through the scanning process on that hamstring,” Merriman said.

“It’s a high-grade hamstring injury and unfortunately that will require surgery which is getting done today.

“Oscar has also gone through the scanning procedure, and we have got some information back so far.

“It’s going to be on the longer-term this injury, we just need to wait for that knee to settle to work out what sort of intervention is required.”

Karl Worner returned to the Club on Tuesday in good spirits following a nasty head knock on Sunday afternoon, with a timeline still to be confirmed on his return.

“He’s actually feeling really good, Karl’s was a pretty nasty one so our number one priority is that we maintain Karl’s health and get him back to feeling great,” Merriman said.

“We will know more in the next few days in regards to his return to play, but we just want to take it easy at this stage.”

Midfielder/forward Jaeger O’Meara was a late withdrawal from the round one clash with a minor knee concern and has been listed as a test for selection this week.

“He’s tracking well, he’s a test to play this week,” Merriman said.

“He had a little bit of knee soreness and we didn’t want to risk him. It’s a long season so just going into round one we didn’t want to risk him too much.”

Merriman also provided some positive progress markers on ruck Sean Darcy and winger Nathan O’Driscoll as the pair work to rehabilitate knee injuries.

“Sean is tracking as planned, he’s on the Alter-G (anti-gravity treadmill) running at about 65-70 per cent of his body weight,” Merriman said.

“He will progress further on the Alter-G and hopefully progress to on-field later in the week.

“Driz ran on-field on Saturday, he’s progressed really well and is roughly about two-to-three weeks away.”

ROUND TWO INJURY LIST:
Jaeger O’Meara (knee) – test
Ethan Stanley (ankle) – 2 weeks
Karl Worner (concussion) – 2 weeks
Nathan O’Driscoll (knee) – 2-3 weeks
Sean Darcy (knee) – 3 weeks
Heath Chapman (hamstring) – 3 weeks
Corey Wagner (calf) – 5-7 weeks
Brennan Cox (hamstring) – 12-14 weeks
Oscar McDonald (knee) – TBA
Odin Jones (concussion) - TBA
Josh Corbett (hip) – Season
Sebit Kuek (knee) - Season