Sydney defender Nick Blakey has avoided a concussion following a tackle from St Kilda's Dan Butler that was adjudicated as 'dangerous' during Thursday night's match at the SCG, with the case potentially gaining the attention of the AFL's Match Review Officer.

Concerns sparked during the third term of the Saints' 14-point win over the Swans after Blakey was subbed out moments after the tackle in question, with the newly-re-signed backman undergoing a head injury assessment (HIA) after his head crashed into the turf as a result of a powerful Butler tackle.

Offering clarity in his post-game press conference, Sydney coach John Longmire revealed Blakey had not failed his HIA, and instead had been subbed out of the match due to a prior foot/toe concern as the club looked to avoid waiting a full 15 minutes for the injury report to be made and be left one man down during a tight contest.

"He passed his HIA he was fine in the end," the premiership coach said.ย "It was going to take 15 minutes by the time he was assessed and allowed back on the ground, which was pretty critical at that point.

"He had a toe injury coming into the game and we had to get moving; it was a pretty important part of the game, 15 minutes is a good slab of time.

"With his toe being sore we made a change. It was only last week that he hurt it and he came into the game a bit sore. Hopefully he will be OK next week."

Should Blakey remain cleared of concussion symptoms, Butler's chances of a suspension, or even charge, from the MRO could be influenced in the grading of the tackle.

For Butler's actions to be deemed a reportable offence, the MRO would need to view the tackle being made as 'careless' conduct and "unreasonable in the circumstances".

A rough conduct dangerous tackle charge against Butler could be handed down if the MRO views his actions in the tackle on Blakey as "inherently dangerous", or if he believes Blakey was placed in a "vulnerable position" with "little opportunity to protect himself", or that Blakey was "driven into the ground" with "excessive force".

Should the MRO assess Butler's conduct as 'careless' and charge the Saints forward with rough conduct, the degree of impact will likely then decide whether Butler might come away with a fine or suspension.

READ: HOW THE MRO SYSTEM WORKS

With the grading of contact likely to be graded as 'high', coupled with the careless conduct grading, Butler would need an impact grading of 'low' to avoid a suspension. An impact grading of 'medium' would see Butler handed a one-game suspension, with a 'high' impact grading resulting in a two-game suspension.

The MRO will release their findings from Thursday's match on Friday evening.

St Kilda are scheduled to face Richmond in Round 14 at the MCG before a return to Marvel Stadium against Brisbane the following week.