Watford sealed automatic promotion back to the Premier League at the first attempt after a narrow home win over Millwall.
Ismaila Sarr's composed 11th-minute penalty, after the Senegal winger was brought down in the box by Billy Mitchell, proved enough for the Hornets.
Mitchell drew a save from home keeper Daniel Bachmann before the break with a shot from outside the box before Mason Bennett saw his follow-up effort clip the top of the bar.
Bachmann clawed away a close-range effort from a corner as Millwall pressed for an equaliser in the second half, but Watford held on to secure an eighth successive league victory at Vicarage Road.