Andreas Pereira was impressed with his young teammates in Thursday's win over AZ Alkmaar.
Ole Gunnar Solskjaer started teenagers Brandon Williams, James Garner and Mason Greenwood, who fired in a double.
Pereira told BT Sport: "The manager said to press like a team, press them more and be compacted. It worked out well.
"The youngsters have been playing well. Hopefully we can keep it up. Good teams are coming now and we have to see who we take next. We have to be prepared."