Northampton Saints coach Jim Mallinder denied that George North was allowed to play on after being knocked out in Saturday's Premiership defeat to Leicester Tigers.
Saints went down 19-11 to their local rivals at Welford Road, but North's head injury overshadowed the result.
Contesting a bouncing ball with Leicester try-scorer Adam Thompstone, North was caught in mid-air by his opposite winger and tipped before landing on the turf on his side.
North's head crashed towards the ground as he fell and the Wales international was left prone on the turf and was then taken off the field for a Head Injury Assessment, which he passed before returning to finish the game.
The 24-year-old missed five months of 2015 after a series of concussions within a similar timeframe, prompting concerns over this latest blow, but Mallinder was firm in claiming that the rules had been adhered to by his medical staff.
He told BT Sport: "If you get knocked out you can't go back on, it's one of those things. If you're knocked out you don't go for an assessment.
"So, no, he wasn't knocked out. He went out, he was fine. The doctor was perfectly happy with him and we were happy for him to continue."
Mallinder's opposite number, Richard Cockerill, said the Saints boss would have been powerless to stop North coming off, as coaches must put their faith in the medics.
Cockerill said: "You have to trust the medical teams don't you. You trust their opinion.
"Once they get on the field and they're dealing with the player that's motionless - it's their call. It's not the coach's call, it's the medic's call.
"We've got Dom Barrow and Telusa Veainu on stand-down periods at the moment because of that so you have to trust the doctor to make the right call independently and trust their opinion."