Answer
Saúl Ñíguez was loaned to Rayo Vallecano during the 2013–14 season. He was a member of the first team at Atlético Madrid, but he was loaned out to Rayo Vallecano in order to gain more playing time. He made 26 appearances for Rayo Vallecano during the season, scoring three goals. He returned to Atlético Madrid at the end of the season.