The AFL has reprimanded Collingwood's Mason Cox following an incident ahead of last Saturday's clash between the Magpies and GWS.

Footage captured Cox running into Giants ruck coach Shane Mumford minutes out from the opening bounce as both teams looked to warm up at the centre circle, with the league having since sent the American a 'please explain' for his actions.

The AFL released a statement on Tuesday, stating it "should have been plainly apparent to Cox" that Mumford and other members of the Giants were occupying the centre of the field when he decided

Cox has been issued a reprimand by the league, who stressed the importance that "players conduct themselves professionally"

"The AFL has completed its inquiries in relation to Mason Cox's conduct prior to the commencement of the Opening Round AFL Match between GWS GIANTS and Collingwood at Engie Stadium,"

"After receiving a statement from Collingwood and Mason, speaking with the umpire and reviewing the vision, whilst the umpire did agree to another bounce as requested by Cox, it nevertheless should have been plainly apparent to Cox that GWS Coach Mumford and multiple GWS players had congregated in the centre circle by the time the relevant bounce occurred.

"Noting Cox's contrition and the Club's commitment in supporting him to be more aware in the future, the AFL has determined to issue a reprimand to Cox and take no further action.

"It is important that all players conduct themselves professionally particularly during breaks and in the periods prior to and following matches."

Cox issued an apology for his actions earlier in the week, offering some insight into his decision-making.

"I apologise for the incident in our pre-game where I made contact with a GWS official," he said in a statement.

"In the moment, I was solely focussed on getting one more bounce in – in hindsight, I should have stopped my run-up rather than completing the drill."

Cox and Collingwood will face Sydney at the MCG on Friday night as the Magpies look to rebound from their Opening Round loss to GWS.