Lukaku joined United over the summer for a fee that could rise to £90 million and it took him just 35 minutes to open his account for his new club.
By scoring twice here, with Anthony Martial and Paul Pogba's late strike crowning a 4-0 victory, Lukaku not only extended his own healthy scoring record against the Hammers but eased fears of the same old problems rearing their head.
Mata was through again shortly after following a lovely looped pass over the top by Pogba, but the Spaniard's square pass for Lukaku at the far post was cut out.
RCB - Chris Smalling: You'd expect more centre-backs to be given opportunities by José Mourinho this season, with the Portuguese testing out a new 3-5-2 formation in some of the preparation fixtures and at the start of the UEFA Super Cup. He was everywhere, and the best player on the pitch at times. Mourinho expectedly gives the Old Trafford debut to Romelu Lukaku, spearheading an attacking lineup that includes fringe starters Marcus Rashford and Juan Mata.
Dovizioso wins stunning Austrian Grand Prix
Alvaro Bautista secured an eighth-placed finish for Aspar Ducati , with Avintia Ducati's Loris Baz ended ninth. Zarco took fifth after holding off Vino. ales and coming home top Yamaha, with Rossi crossing the line in P7.
Late goal gives Arsenal EPL thriller win
Two minutes later, the comeback was complete, with super-sub Giroud sending the home fans wild via magnificent header from a Xhaka corner, despite being held by Wes Morgan.
Lukaku scored either side of half-time with two well executed efforts.
And the Argentinian paid a heavy price for that foul for, when Mkhitaryan floated over the consequent free-kick, that man Lukaku ghosted in front of Masuaku to nod home his second goal of the afternoon.
But there there was to be yet more Manchester misery for West Ham in the final three minutes as Mkhitaryan invited Martial to race behind the visitors' defence and calmly slot past the helplessly exposed Hart.
Paul Pogba has now scored 34 league goals since 2012/13; 16 of them have come from outside the box. Great from Pogba, awful from Hart. His ability to get the out of the defensive third so quickly could prove to be crucial for Mourinho's counter-attacking style, and should be given a chance to shine in the Premier League.
Trump to call for China IT trade probe on Monday
The forced sharing of intellectual property with Chinese firms has been a long-standing concern of the USA business community. On Saturday, administration officials said the new trade measure was "totally unrelated" to events involving North Korea.
YY Inc., (NASDAQ:YY), Rowan Companies plc, (NYSE:RDC)
According to analysts Rowan Companies (NYSE:RDC)'s minimum EPS for the current quarter is at $-0.81 and can go high up to $-0.25. The stock moved on high volume, traded at a volume of 1988319 shares, as compared to its average daily volume of 1.24M shares.