A new era for West Ham got off to the perfect start, albeit with a nervy victory over Sheffield United.
Mullins' second goal of the season proved decisive
Fresh from his takeover, Eggert Magnusson was given a rousing reception at Upton Park before kick-off.
And the Icelander was on his feet applauding when Hayden Mullins headed the Hammers in front on 36 minutes.
But the hosts had to hang on after the break and were grateful to referee Mike Riley when he controversially ruled out Robert Kozluk's goal at the death.
606 DEBATE: Give your thoughts on the match
Riley spotted a foul on Hammers keeper Rob Green, who came through a crowd of players to clear Mikele Leigertwood's hopeful punt into the box.
Blades boss Neil Warnock and his entire team were inevitably enraged by the decision and an equaliser would not have been undeserved for the battling Blades.
Before kick-off, Magnusson, holding his rather bemused two-year-old grandson Eggert, was serenaded with a rendition of 'I'm Forever Blowing Bubbles' as the home fans celebrated the end of an uncertain period in the club's history.
The Icelander had spoken warmly about maintaining the club's long traditions but one of those, that of playing attractive, passing football, was not in evidence in the first half.
If anything, Alan Pardew's side seemed a little too keen to impress their new chairman in an opening period which was furiously contested but featured an array of misplaced passes.
Lee Bowyer fashioned a rare chance when he floated a free-kick from inside his own half into Carlos Tevez's path but the Argentine could only find the side netting.
The Blades were their usual competitive selves but lacked a cutting edge up front.
The closest they came to breaking the deadlock was a long-range effort from Alan Quinn which clipped the top of the net after 20 minutes.
Bowyer should have put the hosts ahead when Bobby Zamora set him up six yards out but the midfielder's weak shot was deflected wide.
However, Mullins quickly saved Bowyer's blushes when, from the resulting corner, he headed in Anton Ferdinand's flick-on from close range.
The goal, though, did little to settle West Ham's nerves and they were put under severe pressure in a tense second half.
Blades substitute Christian Nade had only just arrived on the pitch when he burst through, only to take a fraction too long to get his shot in, allowing Danny Gabbidon to slide in with a well-timed tackle.
The Costa Rican should have equalised three minutes later when Keith Gillespie picked him out with a stunning cross - but the striker skewed wide.
The arrival of a thunderstorm accompanied by torrential rain appeared to take the sting out of Warnock's side and West Ham could have extended their lead.
Bowyer took advantage of a slip by Kozluk on the left and crossed for Nigel Reo-Coker, who looked more than a little sheepish when he completely miskicked his attempted half-volley.
Mullins and Marlon Harewood also squandered good chances before the late drama involving referee Riley and the goal that never was.
West Ham boss Alan Pardew:
"There was a lot of pressure today, with the new owner and a game against a team who were always going to make it difficult.
"It was tense and I was very pleased to come away with a win and a clean sheet.
"The uncertainty about the club created a very disturbing situation but now we have a very enthusiastic new owner - and we've produced a gritty display."
Sheffield United boss Neil Warnock:
"The disallowed goal at the end was unfortunate. Referees should learn more from managers about the game.
"But it's like climbing glass mountains for us: we make basic mistakes at the back and we're not taking our chances.
"But the Premiership's great isn't it? I know we're struggling but I love it."
West Ham: Green, Spector, Ferdinand, Gabbidon (McCartney 64), Konchesky, Bowyer, Mullins, Reo-Coker, Etherington, Zamora (Harewood 73), Tevez (Sheringham 66).
Subs Not Used: Kiraly, Benayoun.
Booked: Mullins, Bowyer.
Goals: Mullins 36.
Sheff Utd: Kenny, Kozluk, Jagielka, Davis, Geary, Gillespie (Kazim-Richards 76), Law , Leigertwood, Alan Quinn (Nade 59), Montgomery (Kabba 59), Hulse.
Subs Not Used: Bromby, Morgan.
Booked: Montgomery, Gillespie, Hulse, Kozluk.
Ref: M Riley (W Yorkshire).