"For the three boys, (it) was fantastic", he said, according to Sky Sports.
Pulisic will feel more at home at Stamford Bridge, where the smaller pitch will enable him to be more effective but he needs to make an early impression on his own terms, for his own sake, to avoid being regarded as a shadow of the man he replaced.
"For them and for me, you just couldn't write it".
Head coach Lampard said: "We were clearly the better team for 45 to maybe 60 minutes".
'I think everyone was raring to go anyway, but we can't get carried away.
"Had we gone in at half-time 2-1 or 3-1 up, which we should have done, the game would have been completely different".
It was a clinical display from Solskjaer's team in the second half with three goals in 16 minutes, but James insists there is still room for improvement.
"My feeling is that today they had a possibility to play with more know-how", Mourinho said. We will have to learn harsh lessons and correct them pretty quickly. "It was a very good match to start with from the whole team".
"We are missing internationals and big players but I don't want that excuse", said Lampard. "There's a reality check for us all".
"You can be very risky in attack but if you feel that a mistake is around the corner it takes your confidence away and you don't play as well".
Lampard's new-look side continued to show promise as the second half got under way, only for United to show a ruthless edge sorely lacking in recent seasons.
"They pinned us back and created chances but we settled a few nerves. We need to make it a fortress".
"It's quite hard to talk about it after 4-0, you can sound stupid but anyone who watched the game would have seen that".
Lampard was reluctant to dwell on the positives for his team but was justified in his view that the scoreline did not reflect his team's performance with the ball. We took risks but that's the way here. We were lucky to have the lead through the penalty in the first half, but after a bad start, we finished the match well.
"For me, it was just going out there and enjoying it, and obviously if I get an opportunity try and take them, and thankfully I did".