The two keepers are together with the Spain squad this week. Like De Gea, Kepa is a target for Real Madrid.
[Kepa] is still very young," said De Gea. "He has a long career ahead of him.
"His head is very settled but he must keep growing. When training with him, you realise his level and that he is a great goalkeeper.
"I'm young too, we are both here and, with Pepe [Reina], we always arrive at the national team with the greatest enthusiasm to help the side."