Casillas, 32, has played second fiddle behind Lopez this season with new coach Carlo Ancelotti, continuing the pattern from last campaign which saw him benched under Jose Mourinho
The Spain international is reported to be considering his long-term future with the club, yet former Blancosshot-stopper Buyo believes that Lopez has earned his place in the Madrid line-up.
"If a player is unhappy and does not play, he always wants to improve and play," he said to Marca.
"The performance of Diego Lopez is still outstanding, stellar and is to a very high standard, at the height of the best goalkeepers in the world."
The Blancos veteran, however, believes that if Casillas is truly unhappy then it is up to the Spaniard to move on from the Santiago Bernabeu.
