Sheffield United and Derby may settle their contest on the ball after the first clearance. United have wide delivery and a second runner; Derby can answer through Morris and quick releases. At Vallecas, Rayo's wing entries should meet an Elche side looking for a quick direct escape. The next reception after a blocked cross matters in both matches.
United's Burrows and Chong played against Bristol, and Arblaster has shown he can collect and finish the loose ball. Derby's adapted back line remains in use, Travis missed its last game and Mowatt's fitness is uncertain, narrowing the screen in front of it. United can keep pressure on after the initial delivery and protect territory after scoring. That's why I'm siding with Sheffield United to win.
Rayo retain De Frutos and Álvaro as wide suppliers, with Ciss available to gather the next ball despite an older conflicting absence flag. Elche lost Aguado during its last match and has recently needed Dituro to stop repeated close efforts; Audero and Rayo's central pair have played together. Sustained Rayo entries can turn one of those second contacts into the decisive finish. That's why I'm siding with Rayo Vallecano to win.