"Momo is as important as Steven because he can play in the middle and work and cover when Steven is attacking from different avenues," said the Spaniard.
"He has done so well, he arrived as a very young man in Spain speaking only French and had to learn the language, then a couple of seasons later he has arrived at Liverpool and has to learn English.
"This is not easy for anyone, certainly not someone so young. I am very pleased with him because he has been an impressive person on and off the pitch.
"He has become so important for us. He gives us a physical power that is vital in top-class football these days."