A fresh muscular injury picked up by Hernandez in training will rule the Spaniard out for around three weeks while striker Roofe will also miss the clash at The Den having picked up a kick in training.
Fellow striker Bamford is facing around four months out with a posterior cruciate ligament knee injury and a knee injury will also force Berardi to miss Saturday's encounter at Millwall.
Asked about his team news at Thursday's pre-match press conference, Whites head coach Marcelo Bielsa said: "Berardi still needs time to come back. Bamford needs a little less than four months. For Pablo, it will be more than three weeks. And Roofe will not be able to play either. He received a kick that does not allow him to play the next game so we have four players missing."
Berardi injured his knee towards the end of the recent goalless draw against Middlesbrough at Elland Road while £7m summer signing Bamford damaged his posterior cruciate ligament playing for United's under-23s against Bristol City's development side last Friday.
Hernandez, though, had returned to training this week having suffered a muscular injury in the 3-0 win at Norwich City.
Bielsa added: "Pablo has a muscular injury, he felt a point in the last game he played.
"He got well and recovered but in the preparation in this game against Millwall he felt another point but I don't know if it's the same injury but it's in the same muscle."
With strikers Roofe and Bamford also both sidelined, 19-year-old Tyler Roberts is set to lead the Whites line in Saturday's clash at The Den.
Asked what his options upfront now were, Bielsa said: "The first option we have is Tyler Roberts and we have also other possibilities."