Hasselbaink, who has scored 15 Premiership goals, left the field against Charlton last week with a hamstring problem, and that is likely to lead to 18-year-old Alan Smith partnering the 20-year-old Harry Kewell up front in one of the youngest strike pairings to grace the Premiership.
Hopkin has an ankle injury and with Alfie Haaland on international duty with Norway, Gunnar Halle out (knee) and Bruno Ribeiro (knee) also struggling it could lead to a recall for Stephen McPhail. The midfielder has only just returned from Nigeria where he has been on Republic of Ireland duty in the World Under-20 Championships.
After seven consecutive wins Leeds have drawn their last two matches and tomorrow is the start of a run-in that sees them play all three teams above them in the League.
Leeds have a good record against their arch rivals at Elland Road in recent years, winning three of the last four - the only loss in that time, 4-0 in 1996, effectively forcing the dismissal of Howard Wilkinson.
In the last 10 years, four League games have ended goalless while in the fixture at Old Trafford in November David O'Leary's young side gave an excellent account of themselves before losing 3-2.
Manchester United must squeeze six matches into the last three weeks of the League campaign and Alex Ferguson will have to make sweeping changes for the game which has an 11.30am kick-off. Ole Gunnar Solskjaer and Ronny Johnsen join Haaland on international duty with Norway, while Jaap Stam, Ryan Giggs, Paul Scholes and Andy Cole are struggling with injuries.
Stam has Achilles trouble, Giggs is still recovering from his ankle problem, while Scholes has a sore knee and Cole an ankle complaint.
The loss of Stam would be a huge blow to United as they are already missing two other centre-backs, Johnsen and Henning Berg, who has a medial knee ligament injury.
Ferguson could turn to David May, who came on as a substitute against Sheffield Wednesday last week for his first taste of Premiership action this season, and Wes Brown, named on Thursday alongside Leeds' Jonathon Woodgate in Kevin Keegan's England squad for Hungary, or move Gary Neville across from right-back.
LEEDS UNITED (from): Martyn, Radebe, Wetherall, Wijnhard, Hasselbaink, Ribeiro, Bowyer, Hopkin, Granville, Kewell, Harte, Knarvik, Batty, Woodgate, McPhail, Smith, Jones, Robinson.
MANCHESTER UNITED (from): Schmeichel, G Neville, Irwin, May, Beckham, Butt, Cole, Sheringham, P Neville, Curtis, Blomquist, Giggs, Keane, Van Der Gouw, Scholes, Yorke, Nevland, Clegg, Casper, Brown, Greening.
Referee: D Gallagher.