Referee Ben Whitehouse has come under fire after his performance in Clermont's 24-7 victory over Northampton at the Stade Marcel Michelin.
Morgan Parra was allowed to return to the game following a Head Injury Assessment (HIA) after his head connected with Luther Burrell's knee as he attempted to tackle the Saints' centre.
BT Sport commentator Ben Kay said on TV at the time: "The referee said he was unconscious, he's not allowed to come back on to the field. The referee has the power to say he cannot continue."
Parra brought back on despite referee stating he was unconscious.— RugbyLAD (@RugbyLAD7) October 21, 2017
The HIA fails once again. pic.twitter.com/AvrFWXoiEK
The rules state that if a player is knocked unconscious there is no grounds for a HIA but Parra underwent the tests and returned to the game.
Clermont came out on top as tries from number eight Fritz Lee, a Charlie Cassang brace, and an effort from prop Etienne Falgoux gave the French side a bonus-point success.
Lock Christian Day crossed for Northampton but England captain Dylan Hartley and France international tighthead prop Rabah Slimani were both yellow carded in an ill-tempered affair.
Saints were furious Slimani was not sent off for a deliberate shoulder charge on Hartley and director of rugby Jim Mallinder said: "When you come away to a place like this is you need a strong referee or sometimes these things happen.
"There were a couple of crucial decisions that went against us and we will look back at some of those. There was lots of good play, but we just weren't accurate enough when we got five metres out."
Mallinder added: "This is a fantastic place to come and play rugby. The noise is unbelievable and I think the lads enjoyed the atmosphere but we're disappointed we didn't get some things right.
"We had more possession and territory but we need to take our chances. We were disappointed to concede just before half-time and then there was the score just after the break.
"We need to forget about Europe for a while, but next week against Wasps becomes a huge game for us. It's a home match, we're third in the league, and it's one we're looking forward to."
Clermont lost France international fly-half Camille Lopez in the first half to a horror leg injury, but they responded to lead 14-0 at the break.
Lee opened the scoring from a powerful line-out and Cassang - who had replaced Lopez - made it two for Clermont just before the break. Morgan Parra converted both scores.
Saints lock Courtney Lawes had a try ruled out, and Hartley's yellow card for charging into Slimani did not help the home side as they briefly went down to 13, allowing Cassang to score.
Cassang added his second when the game resumed, but Northampton refused to go away and Day got them on the scoreboard with Harry Mallinder converting.
Saints were then handed a lifeline when Slimani was given a yellow card of his own when he ran into a ruck and hit Hartley.
It was that incident which so enraged Mallinder and his mood soured further when replacement prop Falgoux grabbed the hosts' bonus point.
Clermont face a double header with Saracens - a team they met in last season's Champions Cup final - when European action resumes in December.
Their replacement back Scott Spedding said: "We are not going to worry about Saracens for the moment.
"If you leave points out there in this competition, it costs you very dearly and we need to improve in that regard.
"Saracens is to come, but they have shown in the past they are a very strong team and they are chasing a third straight title. They'll be one to watch out for I'm sure."