Arsenal goalkeeper David Ospina collapsed during Napoli's Serie A win over Udinese and was subsequently taken to hospital.
The Colombian is on loan with the Italians for the season and suffered a blow to the head in a collision with Ignacio Pussetto.
Shortly after the visitors levelled the game at 2-2, having previously been 2-0 down, Ospina fell to the ground before the interval.
After receiving treatment on the pitch, Ospina was substituted and taken to hospital, where he underwent tests and treatment.
"Fortunately it's nothing serious, he's conscious," said manager Carlo Ancelotti. "They did a CAT scan that is negative."
The Partenopei went on to win the game 4-2, with goals from Arek Milik and Dries Mertens.
Ospina could feature against the Gunners in the quarter-finals of the Europa League, though it remains unclear whether his parent club inserted a clause forbidding his involvement.
Uefa rules allow loan players to feature against their parent clubs though, as was the case with Thibaut Courtois when he played for Atletico Madrid against Chelsea in 2014.
But Ospina has not been Ancelotti's No 1 throughout the campaign, battling with Alex Meret for game time.
The 30-year-old's appearances have been restricted with the belief that Napoli must make his loan move permanent if he reaches 30 games and his current total at 17 in all competitions.
