Sanchez Flores has urged his Watford players not to fall into the trap of taking Manchester United's injury-hit team lightly.
Injuries to the likes of captain Wayne Rooney, Chris Smalling and Phil Jones has seen Louis van Gaal blood a number of academy graduates.
Indeed defender Tim Fosu-Mensah and midfielder James Weir were the latest to be handed their debuts in United's 3-2 victory over Arsenal on Sunday.
Watford head to Old Trafford to face Van Gaal's patched-up side in the Premier League on Wednesday night. But Flores does not believe United's star-studded treatment room makes them any easier a proposition.
"I don't like to say to the players, 'come on boys, now Manchester United are a little bit weak because they have injuries, because they are younger, because they don't have experience', no, it is the opposite," said Flores.
"I try to send other messages to the players, saying take care and don't relax. Yes, they are younger, but they have a lot of passion, and they want to show everyone they are ready to play in the Premier League.
"So, of course we will play a very tough match, and this is the idea we try to translate to the players. Maybe this is not the best XI they have in the squad, but they are playing really, really well."
Marcus Rashford made his Premier League debut in the victory against Arsenal on Sunday and the 18-year-old product of the United academy followed up his brace in the 5-1 Europa League win against FC Midtjylland with another double to take his tally to four goals in just two matches for the club.
"He looks really good and I love younger players," Flores added. "I love how he moves to the space and how he moves inside the box.
"He is a very good talent for the future of England and very good news for Manchester United.
"With the younger players when they knock on the door, as a coach you need to open the door and say 'okay you are ready to go' and this is what has happened.
"Manchester United have had a lot of injuries, a very difficult period for them, and this is the moment when the younger players use the opportunity to establish themselves in the team."
Asked if he had a plan in place to stop Rashford on Wednesday night, Flores joked: "It is impossible to show too many videos [to my squad] because he has played only two matches."