Ed Cowan has been ruled out of the remainder of NSW's Sheffield Shield match with Western Australia after being struck on the head by a fierce bouncer on Friday.
The former Test opener is in a "reasonable state", according to Cricket Australia, after the vicious blow, but under the new concussion guidelines implemented by the governing body, he will be under observation for the next 24 hours.
Cowan hit and concussed by bouncer
NSW opener Ed Cowan has been ruled out of the rest of his side's Sheffield Shield match against WA after being hit by a Joel Paris bouncer.
He is the first player in an Australian first-class game to be taken off the field under the policy introduced last year.
Cowan was struck late on the third day in Christchurch by a bumper from Joel Paris, collapsing to the ground momentarily before climbing to his feet unaided.
The clearly rattled batsman acknowledged the concerns for his welfare shown by his opponents before walking to square leg to regather his composure.
He spent several moments on his haunches before being assessed by CA's chief medical officer Dr John Orchard and heading off the field.
"Ed suffered a hit to the front of his helmet during his batting innings," a CA spokesman said. "As per the Cricket Australia concussion guidelines he was assessed on the spot by the Cricket NSW doctor and retired from the game hurt.
"Advice from the doctor is that Ed's health is in a reasonable state but per the Cricket Australia concussion guidelines, he will be observed for the next 24 hours as a precautionary measure and not take further part in the match."
Before the new rules were introduced, Cowan may have been allowed to bat on, but cricket authorities are now taking a hardline stance on head injuries following the tragic accident that claimed Phillip Hughes's life in 2014.
The incident was the sour point on a day when Test batsman Adam Voges continued his sterling form against the red ball.
Voges warmed up for the first Test next week against New Zealand by hitting 149 to lead a fightback by the Warriors.
Test spinner Nathan Lyon claimed 3-146 from 45.5 overs.
The Shield game appears to be heading towards a draw with the Blues to resume on the final day on 1-11, trailing WA by 78 runs.