Interim boss Ralf Rangnick says disruptions caused by Covid-19 have impacted his progress since taking over at Manchester United.
The German, 63, is unbeaten in four games since replacing Ole Gunnar Solskjaer at the end of November.
But he says the Covid outbreak that led to the closure of the club’s Carrington training base and the postponement of two games has complicated his work.
“Of course not,” Rangnick said when asked if he had achieved his targets.
“Every coach, every ambitious coach – and there’s no difference between other coaches and myself in that area – wants to take faster steps and larger steps forward.
“But in order to do that, you need to be able to train.”
After beating Crystal Palace and Norwich either side of a Champions League draw with Young Boys in Rangnick’s first three matches, games at Brentford and at home to Brighton were postponed because of a number of Covid cases at United.
They returned to action at Newcastle on Monday, with Rangnick admitting that he “did not like the performance at all” as his side escaped St James’ Park with a 1-1 draw.
“The last three days, we were almost back to full strength with regard to the size of the squad, but we couldn’t do that much in training,” he added before Thursday’s home match against Burnley.
“On the other hand, in those two-three training sessions, the team looked good and therefore in Monday’s game it was really a bit of a negative surprise, the way that we played with regard to game speed, game tempo and physicality.”