Courtney Lawes will be forced to go through concussion protocols after suffering a blow to the head in the British & Irish Lions' defeat to the Highlanders on Tuesday.
Lawes sustained the injury as he attempted to tackle powerhouse wing Waisake Naholo, who charged towards the line for a try.
The Saints lock appeared to be knocked out and eventually left the field looking groggy.
Lawes, who had been impressive during the opening 20 minutes of the match, was replaced by Wales second row forward Alun Wyn Jones.
And the Saints star will now hope for a speedy recovery with the Lions' first Test against New Zealand taking place at Eden Park in Auckland on June 24.
"Courtney will go through the HIA protocols," confirmed Lions boss Warren Gatland after his team's 23-22 defeat.