Hearts manager Robbie Neilson has been asked by the Scottish Football Association to explain comments made about match officials after the club's recent 3-2 defeat by Hamilton Academical.
The 35-year-old was critical of referee Willie Collum after a red card was shown to defender Callum Paterson, a decision since overturned.
Neilson said after the match: "We actually practised during the week going down to 10 men because of the environment we're coming to and the officials who are taking the game and we have to do that.
"In the recent past, the statistics involving the officials have shown a lot of red cards against us, so we have to prepare for it. The next time we get these officials, we will again train with 10 men."
Hearts sit third in the Scottish Premiership table after six games.
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