Two fine goals from Ronaldo sent Real on their way to all three points, as they looked the far better side at La Mestalla.
Ronaldo's first goal was fine header in the first half but Valencia went into the break level after Fabio Aurelio struck a fine right-foot shot past Iker Casillas.
However, Ronaldo wrapped up the points in the second half after fine Luis Figo ball forward was sublimely controlled by the Brazilian ace and he rounded Santiago Canizares to make it 2-1.
The win takes Vicente Del Bosque's side two points clear of Real Sociedad, who are away to Malaga on Sunday evening.
Deportivo La Coruna's title chances were dealt a severe blow following a 3-0 defeat at Celta Vigo.
Second half goals from Jesuli and Edu - who had two - were enough to take Celta a point clear in fourth while Depor are now five points adrift of the lead.
Athletic Bilbao left it late to defeat Racing Santander 2-1 at San Mames, as second half goals by Aitor Karanka and an Ismael Urzaiz penalty in the last minute gave the Basque club all three points, despite falling behind to a Pedro Munitis opener two minutes after the break.
Atletico Madrid came from 2-1 down to earn a 3-2 victory over Villarreal at the Vicente Calderon.
A Quique Alvarez own-goal put Atletico in front but goals by Javier Calleja and Josico gave the visitors a 2-1 lead at the break.
However, two goals in the space of four minutes from Fernando Torres gave Atletico the win.
Finally, bottom club Rayo Vallecano could not improve their desperate situation at the foot of La Liga table, following a 0-0 draw with Osasuna.
Rayo finished the match with ten men after Iriney Santos da Silva sent was off for violent conduct with ten minutes remaining.
Click below for match stats:
La Liga
Athletic Bilbao 2-1 Racing
Atletico Madrid 3-2 Villarreal
Celta Vigo 3-0 Deportivo La Coruna
Rayo Vallecano 0-0 Osasuna
Valencia 1-2 Real Madrid
Click here for an updated Liga table.
