Ulster are waiting anxiously for news on centre Luke Marshall following his latest injury.
The 22-year-old midfielder suffered a third head injury in quick succession in Saturday night's 27-16 Heineken Cup quarter-final defeat by Saracens at Twickenham, giving rise to major concern.
Ulster coach Mark Anscombe insisted the player would never have been included had there been any doubts or misgivings about his readiness to return. He was concussed twice in the space of a week playing for Ireland in the recent Six Nations Championship.
Asked if Marshall is likely to play again this season, Anscombe said: "Let the medical team, who are experts in that, tell us this week what the story is.
"It's a concern but we have good medical people involved in this team and we'll do everything that's right for Luke."
Saturday was the third time in as many matches that Marshall has left the pitch after a blow to the head. And although reassuring fans via Twitter that he is 'feeling grand', Ulster's medical team will take no chances with repeated injuries of this nature
In a further blow amid the debris of Saturday's defeat, inspirational Ulster captain Johann Muller is out for the season with a bicep injury. And prop John Afoa has returned to New Zealand for a week and will miss Friday's game against the Dragons.
Marshall suffered a hefty blow to the head in the second half of Ireland's game against France on March 9, resulting in his exit.
Remarkably, he was pronounced fit to face Italy in Rome seven days later, but that, too, ended in similar fashion when he and fellow-Ulsterman Paddy Jackson had an accidental clash of heads in the second quarter. It looked innocuous, but it was enough to end Marshall's involvement.
Afterwards Jackson said: "I looked down and Lukey just seemed to be asleep."
Saturday's European showdown against the Aviva Premiership leaders was his first match since that March 16 incident – Marshall missed Ulster's RaboDirect PRO12 trips to Edinburgh and Dublin – and the fact that it resulted in a third successive head injury is suggestive of a worrying trend.
Marshall, it is feared, is becoming less resilient as a result of repeated blows.
After investigating the dangers of this to boxers in the USA the National Safety Council advised: "If the brain is not given sufficient time to recuperate, it will not fully heal. An unhealed brain cannot function fully and its overall ability to recover from concussions inevitably decreases."
Ulster coach Anscombe will now closely monitor his player's recovery, with Marshall's wellbeing the number one priority.
"At the end of the day you want to win these big games, but first and foremost you look after the individual and I'll never as a coach put a guy on a field if that could risk his health, I can assure you of that," he said.
Marshall himself was keen to resume, but as per the protocol following this type of injury, Ulster tested him fully to ensure he was ready for what they knew would be a bruising battle against opponents famed for their physicality and aggression.
"We didn't rush him back; he had to prove that he was right to play," Anscombe added. "Stuart Olding has been doing a great job for us – you saw that when he came on – and my point is that we wouldn't have rushed Luke back if he wasn't ready."
Concussions are caused by two types of accelerations or forces – a linear straight-on hit or rotational twisting motion, with medical experts believing the latter to be more dangerous as it can cause a rapid 'spinning' of the brain.
On-going research suggests that a series of concussions can lead to serious damage, even brain injury.
Age, too, is a factor, with an American study having suggested that high school footballers occupying the 'skill' positions – quarterbacks, running backs, wide receivers – suffer more intense impacts to their heads than their college counterparts and, therefore, are more susceptible to concussion and severe spinal injury.