Barcelona coach Xavi insists Marc-André ter Stegen is not for sale.
The Germany goalkeeper has been linked with Newcastle United ahead of the January market amid claims Barca management are willing to sell.
But Xavi says: "For us, Ter Stegen is fundamental.
"His commitment, dedication and professionalism are extraordinary. There are times when there are individual mistakes. His footwork is extraordinary.
"He knows he needs to improve in goal but his footwork is excellent. There is no debate, he is one of the best in the world and we must improve him."