Ole Gunnar Solskjaer has acknowledged Manchester United must now take their Europa League form into the Premier League after his side dismantled Partizan 3-0 at Old Trafford.
Goals from Mason Greenwood, Anthony Martial and Marcus Rashford - starting together for the first time - paved the way for a routine win on Thursday, as United ensured their progression from Group L with two games to spare.
Scott McTominay's late injury was the only blemish, though Solskjaer was frustrated by some wasteful finishing early on.
However, with a clean sheet and three well-taken goals, Solskjaer has now demanded his side, who sit 10th in the Premier League with just three wins so far, show improvement domestically.
"That's the foundation, it's a platform to perform from," Solskjaer told beIN Sport .
"We know we've worked on defending this year and have been solid, we just want to see more of this in the Premier League. Score goals, create chances and see smiles on the players' faces.
"Parts of the game were really good, parts of the performance were really high quality.
"You want to see five or six or seven [goals] but at times I think maybe some players started thinking of Sunday, started to recover a bit and we were a bit sloppy at the end but at times we looked really dangerous.
"First 10 or 15 minutes we should have buried the game and it should have been over by then, but we managed to get the goals and got the clean sheet which is always important for confidence for the goalkeeper and back four. Now we can just look forward to Sunday.
"Very happy [with qualifying]. It means in the last two games we can give game time to other players that need it, some players will come back from injury, so we'll use them to of course try to win the group, but it makes me think about resting a few anyway."
Rashford missed several gilt-edged chances in the first half but came up with a superb finish shortly after the break to put the result beyond doubt and, after United's dismal defeat at Bournemouth last time out, the England forward was delighted the side bounced straight back.
"A good performance which is the main thing, very happy, we take the game as a big positive so we move on and improve," Rashford told BT Sport.
"It's something we've been focusing on, as the forward players. Hopefully today was just the start of it and we can keep improving and be more natural.
"That's the main thing, trying to help each other score and score goals ourselves. We have a big emphasis on that and at the same time try to work for the team then it's a big positive.
"The main thing when you lose a game is you want to win the next one, that's the main thing as a player. It's not nice to lose but it feels very nice to win, to put it right and today we managed to do that."