Manchester United midfielders Marouane Fellaini and Ander Herrera are to have scans on injuries suffered in training.
Both picked up ankle injuries and the results of Fellaini's scan are expected on Saturday, with Herrera's unclear.
They will miss Sunday's Premier League match at Sunderland, while Michael Carrick and Jesse Lingard are also out.
"I have seven injuries, last game it was nine, we are progressing," said United manager Louis Van Gaal. "It's a little thin in midfield."
But, Van Gaal will be able to welcome back Dutch striker Robin Van Persie, who missed the opening day home defeat to Swansea.
"Robin is ready to play so that's a big benefit to the team. I am very happy," he added.
Defender Jonny Evans and midfielder Antonio Valencia resumed training on Friday, but both are still out of the running for selection.
Luke Shaw remains a long-term absentee following a hamstring injury sustained in pre-season.
Argentine defender Marcos Rojo, who signed from Sporting Lisbon for £16m on Wednesday, is also unavailable as he awaits a work permit.