City host Costa's Chelsea at high noon on Saturday.
Guardiola said of the Spain international: “He's a top player. I saw him with Valladolid.
“After that he made an amazing season with Atletico Madrid. He's a top player, top scorer. He has very good movement and he runs in behind."
City lie in 3rd place ahead of the early kick-off, but they can overhaul Chelsea and move into top spot with a win.