Marcus Rashford struck twice as United opened their account with a resounding win over Frank Lampard's Chelsea - with £80million new signing Maguire producing a man-of-the-match display.
Maguire made more clearances (seven), more interceptions (four) and more blocks (two) than any player on show as Ole Gunnar Solskjaer's side made the perfect start to the new season.
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United kept just two clean sheets at home all last season, with the previous shut-out coming in February, and Maguire told Sky Sports:
I was reiterating on the pitch that even at 3-0 and 4-0, we wanted a clean sheet. We knew going into the game that we'd only kept two clean sheets all year here, and so we really have to make this place a fortress and a hard place to come and score.
"It's a good start, but we're not going to get carried away. We'll keep working and we'll keep improving. I've only had three or four days with the lads so I'll get better and I'll get fitter.
"With the opening game of the season at Old Trafford, there were a few nerves in the first half, and I don't think we handled the ball well enough and gave it away in dangerous areas and they had a few chances on the counter-attack.
Maguire rises to win the ball from Christian Pulisic
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"But if you give the ball to our front three, we've always got a chance of scoring as they're so dangerous on the break, and the clean sheet is a massive thing as well."
While Maguire purred on his bow, it was an awful start for Lampard in his first league game on the bench for his old club as they struck the woodwork twice in the first half but paid for their defensive frailties.
Tammy Abraham crashed an early drive against the United bar but the hosts got in front with an 18th-minute Rashford penalty after the England forward was pulled down by Kurt Zouma.
Chelsea, who had been the more creative in the opening half, went close to an equaliser when Emerson struck the post shortly before the break.
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But the game turned decisively in Ole Gunnar Solskjaer's side's favour when, after a Rashford led counter-attack, Anthony Martial bundled in a low cross from Andreas Pereira in the 65th.
Two minutes later, Chelsea's defence was again exposed when Rashford timed his run to perfection to latch on to a long ball from Paul Pogba and beat goalkeeper Kepa Arrizabalaga with a confident finish.
Substitute Daniel James, a close-season signing from Swansea City, then marked his United debut with the fourth, firing into the bottom corner via a deflection after being set-up by Pogba.
"It's a great start for myself and for the team," Maguire added.
We rode our luck a little bit at times during the first half. We gave them too many chances and we were a bit sloppy on the ball, but in the second half we were a lot better.
"We were a lot more ourselves and controlled the game, and I think we thoroughly enjoyed the three points in the end."
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