On the back of the disappointing 3-1 defeat at Sheffield United, Carrick has dropped Ryan Giles, Samuel Iling-Junior, Finn Azaz and Delano Burgzorg.
Neto Borges starts at left-back, with Dan Barlaser, Morgan Whittaker and Tommy Conway also coming into the side.
Dael Fry is missing because of illness. Anfernee Dijksteel returns to the bench after his recent spell out with injury. Josh Dede is again named among the substitutes.
With Barlaser coming into the side, Boro will either play with a midfield three or with Hackney further advanced.
Conway is making his first start since suffering a hamstring injury on Boxing Day, while Whittaker comes back into the side after being left out at Bramall Lane.
Middlesbrough: Travers, Ayling, van den Berg, Edmundson, Borges, Barlaser, Morris, Hackney, Whittaker, Conway, Iheanacho
Subs: Glover, Burgzorg, Dijksteel, Azaz, Forss, Giles, Iling-Junior, Dede, McCabe
Watford: Selvik; Andrews, Keben, Abankwah, Larouci; Louza, Dele-Bashiru; Sissoko, Kayembe, Chakvetadze; Doumbia.
Subs: Bond, Ngakia, Sierralta, Pollock, Ince, Vata, Morris, Adu-Poku, Nabizada
