WINGMAN Chris Mayne is set to miss Collingwood's two pre-season practice matches due to concussion, placing him in doubt for round one. 

Mayne was floored at Pies training on Tuesday morning and was assisted from the field by two club medical staff. 

Due to the AFL's new protocols that force a player into a mandatory 12-day break following a concussion, Mayne is expected to sit out Friday's hitout with Geelong and the March 5 AAMI Community Series clash with Richmond. 

The 32-year-old will be free to return to full contact training on Monday, March 8, just 11 days out from the Pies' season-opener against the Western Bulldogs. 

Essendon speedster Andy McGrath will miss the Bombers' scratch match with Carlton this week under the same concussion guidelines. 

It is Mayne's second concussion in the space of six months after having his face shattered in a collision with Carlton's Patrick Cripps late last season. 

Pie Nathan Murphy presents as a potential replacement option should Mayne miss the clash with the Dogs, with the defender training further up the field this season. 

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Tyler Brown could also be used there for a Pies line-up that farewelled wingman Tom Phillips to Hawthorn in the off-season, while Josh Daicos has spent more time playing as an inside midfielder at training this pre-season. 

Meantime, Jordan De Goey was a notable absentee from the 90-minute session on Tuesday, still recovering from a rolled ankle he sustained in Friday night's intraclub that required scans on Monday. 

Midfielder Taylor Adams didn't take part in the match simulation, however was training strongly away from the main group as he ramps up his recovery from a hamstring strain. 

Defender Jeremy Howe again trained strongly after playing minutes in Friday's hitout as he builds to full fitness following last year's nasty knee setback.