de tomás was loaned to rayo vallecano on 1 september 2017. he was the second-highest scorer of the season with 24 goals, including hat-tricks in victories over lorca fc, cultural y deportiva leonesa and cf reus deportiu, as the club from vallecas won the league and were promoted back to the top flight; this haul was a season record for any player in its history, and he was also named segunda división player of the month in february and april 2018.