Mark McCall has said that Saracens lock George Kruis will go through the normal concussion procedure after being lost early against Harlequins.
Kruis came off right at the start of Saracens' first loss of the season to Harlequins, who had their second row James Horwill sin-binned for the incident.
"George is fine. There is nothing wrong other than the concussion. He was knocked out. He'll do the normal checks," McCall said.
"I don't know when a yellow becomes a red. For us to lose George Kruis in the first minute to a swinging arm… I don't know where the boundaries are."
McCall had no issues with the red card to his own player Rhys Gill, for a dangerous tackle on Quins centre George Lowe.
"I think it was a red card. There are no complaints. Rhys has just come on to the pitch, he's trying to make a good tackle and someone else is involved," McCall explained.
"It made it look worse than it is, but you always run the risk in those situations."
Saracens hadn't lost in the Premiership or Europe through 12 matches this season until Saturday's loss at The Stoop, but McCall admitted that his side would have been lucky to win again.
"In general we didn't deserve to win. Our discipline wasn't good enough. They won the scraps and were really up for it," McCall added.
"All those 50-50 battles that we're pretty good at, we weren't so good at. It's disappointing to lose."