Manchester United boss Ole Gunnar Solskjaer outlined his expectations ahead of Wednesday's friendly against Brentford.
United take on the newly promoted Premier League side as they ramp up their pre-season preparations.
Several first team players should be back after missing the games against Derby County and QPR
"We've got kids wanting to play of course," Solskjaer said.
"They've enjoyed the pre-season. We didn't enjoy the quick succession of the goals we conceded at the start of the second half, of course. We've looked at it and we need to tighten up a little bit in the shape in front of the back four and, hopefully, we can see that against Brentford.
"The training group is bigger with more quality and, hopefully, we'll add layer to layer, but, of course, the season starts quickly and we haven't got time to wait for anyone, whoever is the fittest and in the best shape will be in line to play."