Brazilian striker Costa has agreed a deal to join Luis at Atletico in January after being told he wasn’t part of Antonio Conte’s plans at Chelsea.
And Luis, who spent a season at Stamford Bridge in between two spells in Madrid, believes his new team-mate is one of the world’s best.
“(Costa) is the best I have played with,” he told El Mundo.
“I have seen (Juan Carlos) Valeron do things nobody could do. Neymar and (Eden) Hazard are amazing talents, but the player who gave me most trophies was Diego Costa.
“He always scores the opening goal. Because it is one thing to score 30 goals with hat-tricks in easy wins, and another that 20 of those 30 goals are enough to win 1-0. Nobody does that as well as Diego Costa.”
Costa scored 20 goals last season to help Chelsea win the Premier League title but spent the summer in Brazil in order to force through a move away from Chelsea.
He had his heart set on a return to Atletico but the transfer was completed after the transfer deadline, meaning he cannot play for his new club until the new year.
Atletico Madrid face a difficult test at home to Barcelona tomorrow, before travelling to Qarabag on Wednesday in the Champions League.
Chelsea return to Premier League action tomorrow with a trip to rock-bottom Crystal Palace.
