Duff runs in to celebrate with fellow goalscorer Martins
Nigerian Obafemi Martins scored his first goal for Newcastle to help them to all three points away at West Ham.
The former Inter Milan star capitalised on a misunderstanding between Lee Bowyer and Danny Gabbidon to coolly slot home from just inside the area.
Damien Duff gave the Magpies the lead when he latched on to Martins' pass and rifled past Roy Carroll.
Carlos Tevez hit the crossbar from a free-kick for West Ham, and Bowyer narrowly missed with a speculative lob.
The focus of both sets of fans was on their new forward recruits and whether they could finally open their account and justify the hype surrounding their arrival.
In the claret and blue corner was Tevez, the feisty bulldog of a striker who had made a big impact playing in the World Cup for Argentina.
In the black and white corner was Martins, the £10m signing from Inter Milan, who was brought in by manager Glenn Roeder to inject some pace into the side - and, of course, score goals.
Both looked lively and willing, but understandably both were getting used to English game.
Tevez found himself bullied and hassled for most of his time on the pitch by centre-back Craig Moore and full-back Stephen Carr.
Unlike Brazilian league football, English football does not allow a player of Tevez's class to have time on the ball.
The only time he was allowed to display his worth was when West Ham won two free-kicks at the edge of the area in the first-half.
With his first attempt the diminutive Argentine rattled Shay Given's crossbar and with his second he made the Newcastle keeper save low down.
But despite those two moments of brilliance, Hammers boss Alan Pardew felt his Argentine could not last another half, and prior to the start of the second half he was replaced by Marlon Harewood.
So, what about Martins? The Nigerian, paired with Shola Ameobi, worked tirelessly for the cause. And although his first touch is not quite in the Dennis Bergkamp class, his pace and strength is a huge weapon for the Magpies.
He should have given Newcastle the early lead, but screwed his six-yard shot wide of Carroll's goal after he was played in by Ameobi.
But shortly after the break, Martins more than made amends.
The striker won the ball 30 yards from his own goal and sped down the pitch before laying a pass into the path of the supporting Duff, who fired in his first for the Magpies past Carroll from the edge of the area.
And Martins finally got his personal reward when he took full advantage of a mistake between Bowyer and Gabbidon, to slot in a low shot past the West Ham keeper.
The Hammers, who edged the first half, were largely passengers after the break.
But they had their chances with Bowyer coming close to scoring from the halfway line after picking up Given's poor clearance and Harewood heading wide from substitute Yossi Benayoun's cross.
But it was to be Newcastle's day, although the win was soured by an injury to Given, who came off the worse in a challenge with Harewood late in the second half.
Newcastle boss Glenn Roeder:
"Damien is very experienced and great guy to work with. Oba is a different class in training and we'll see some great goals from him.
The ex-West Ham boss also apologised for waving to Newcastle fans which incensed some Hammers supporters.
He added: "If I've upset people I'm sorry, I don't usually get excitable."
West Ham boss Alan Pardew:
"It looked like our Uefa Cup match sapped us.
"Once Newcastle got the first goal it energised them and took the energy away from us."
Pardew also explained why Carlos Tevez was replaced: "He is not used to the Premiership. It was unfair for my team to expect him to make the runs."
West Ham: Carroll, Mears (Mullins 67), Ferdinand, Gabbidon, Konchesky, Bowyer, Mascherano (Benayoun 67), Reo-Coker, Etherington, Tevez (Harewood 45), Zamora.
Subs Not Used: Green, Cole.
Booked: Mears, Harewood, Konchesky.
Newcastle: Given (Harper 86), Carr, Moore, Ramage, Babayaro, Milner, Parker, Emre (Butt 90), Duff, Martins, Ameobi (Sibierski 72).
Subs Not Used: N'Zogbia, Rossi.
Booked: Babayaro, Moore, Parker.
Goals: Duff 50, Martins 75.
Ref: R Styles (Hampshire).