The Teessiders made a winning start to the season against Shrewsbury in the Carabao Cup first round last week, winning 4-3 at the Riverside Stadium.
Our Boro writer Joe Nicholson has picked the side he would play against The Hornets – scroll down and flick through our picture gallery to see if you agree:
9. CAM: Marcus Tavernier
Scored his first goal of the season last week and looked threatening in the final third. Will have to be switched on defensively against a strong Watford side. Photo: Clive Brunskill
10. ST: Ashley Fletcher
Scored 13 goals in all competitions last season and netted a brace against Shrewsbury last week. Photo: Alex Livesey
11. ST: Britt Assombalonga
Has been made Boro's new captain by Warnock. Will be looking to score his first goal of the campaign against Watford. Photo: Jan Kruger