Watford have secured automatic promotion to the Premier League for the 2021/22 season after a one-year absence.
Xisco Munoz's side made sure of a top-two spot with a 1-0 home victory over Millwall, thanks to Ismaila Sarr's 11th-minute penalty.
It is a first-time return to the top flight for the Hornets, having been relegated in 2019/20.
It is the first time since 2009/10 that two relegated sides have sealed automatic promotion the next season.
The 2021/22 campaign will be Watford's eighth in the competition since they were first promoted in 1999/00. Their 11th-placed finish in 2018/19 remains their highest in the competition to date.
The clubs who finish third to sixth in the Championship - currently Brentford, AFC Bournemouth, Barnsley and Swansea City - will compete in the playoffs to determine the third promoted club.
Semi-finals 17 & 22 May
Final 29 May