The Red Devils opened their pre-season with a 2-1 win over Derby County last weekend but were on the end of a 4-2 defeat to Championship outfit QPR on Saturday.
Jesse Lingard and Anthony Elanga were on the scoresheet for the 20-time English champions, but the home side scored three times in the early stages of the second half to effectively end the match as a contest.
Matic has insisted that Man United must "keep working hard", as the club prepare for their third friendly of the summer against Premier League newcomers Brentford on July 28.
"We are not fresh yet and we have had some problems in some positions in the last couple of days. But we are not looking for excuses for this result today, we just have to keep working hard," Matic told MUTV.
"The kids are understanding what they have to do in senior football and I have to say they worked very well. As you know on Wednesday we have another good match, against Brentford at Old Trafford, so we have to keep working and see where we can improve."
Ole Gunnar Solskjaer's side will open their 2021-22 Premier League campaign with a clash against Leeds United at Old Trafford on August 14. body check tags ::