Jose Mourinho believes Marco Silva's Watford are a far better side than the one that gave Manchester United a bloody nose last season.
The Red Devils were condemned to their third defeat in a week in September 2016 as late goals from Juan Zuniga and Troy Deeney gave the Hornets a 3-1 win.
That period remains the lowest ebb of Mourinho's Old Trafford reign and the United boss is aware just how hard it will be to exact revenge on Tuesday evening.
Watford are eighth in the Premier League after their impressive 3-0 win at Newcastle, with manager Silva's fine work leading to admiring glances from rudderless Everton.
"Against Watford I was very upset with Watford's first goal after some guy sent (Anthony) Martial to the hospital and the referee let it go," Mourinho said.
"That is the reason why I was very, very upset at Watford. I think Watford made also progress.
"They have an unusual squad for a mid-table team.
"They have a squad full of very good players who are not normal to be in these mid-table teams. They have a good coach.
"They have improved a lot from last season too."
Mourinho failed to get the better of Silva in their last two meetings, with his Hull side holding United to a goalless draw in the league at Old Trafford just a week after beating them 2-1 in the EFL Cup semi-finals in January – albeit a scoreline that did not prevent the Old Trafford giants from progressing.
Zlatan Ibrahimovic starred as the Red Devils went onto triumph at Wembley and is now pushing for his first start since April, having made three substitute appearances after returning from serious knee ligament damage.
Marcos Rojo has started the last two matches after being sidelined by a knee issue of his own, although should Phil Jones or Eric Bailly return from injury the Argentina international could be protected.
How best to utilise Paul Pogba is another question for Mourinho given the trip to Watford is swiftly followed by a trip to Arsenal on Saturday.
The 24-year-old has impressed since returning from a hamstring complaint, completing his first full match in 11 weeks against Brighton.
Their returns are bolstered by the continued availability of Romelu Lukaku.
Images appeared to show the striker kicking out twice at the Brighton defender Gaetan Bong just before Ashley Young's strike deflected in off Lewis Dunk to secure Mourinho's men a 1-0 win on Saturday.
Lukaku was left sweating on FA action as retrospective punishment for violent conduct would incur a three-match ban, ruling him out of the derby clash with Manchester City.
However, Press Association Sport understands the striker will face no action from the governing body over the incident.
Referee Neil Swarbrick took no action against Lukaku at the time and the incident was confirmed to have been missed by officials at Old Trafford.
As a result, a panel of three former elite referees reviewed the footage independently of one another to advise whether they deemed it a sending-off offence.
The decision had to be unanimous for a charge to be brought and clearly was not as Lukaku has escaped punishment.