Northampton Saints winger George North has been ruled out of his side's European Champions Cup quarter-final with Clermont Auvergne this weekend.
North's health has been a major concern for the Saints after he was knocked unconscious during a collision with Nathan Hughes in last Friday's 52-30 victory over Wasps.
The Welsh international was also knocked out twice during a match against England in the Six Nations, resulting in calls for him to sit out the rest of the season in order to avoid further head injuries.
Saints coach Jim Mallinder has insisted that North is making "good progress" from his latest scare, but confirmed that he will play no part at the Stade Marcel-Michelin on Saturday.
"We won't play him at the weekend. Clearly he had a nasty knock. He's making good progress. The day after he was up and about," Mallinder is quoted as saying by PA.
"He's improving and down there at the moment going to see a neurologist and we'll wait to see what the experts say."
Hughes was sent off and banned for three weeks due to the incident at Franklin's Gardens, while a leading concussion expert has warned that North could be putting himself in danger if he doesn't take a break from rugby.