Italian champions Juventus gave West Ham the belief they could triumph at Manchester City, according to captain Mark Noble.
City conceded and lost for the first time this season when they went down to the Serie A giants 2-1 in the Champions League on Tuesday.
They returned to the Etihad Stadium aiming to make it six wins from six in the Premier League in 2015-16 but first-half goals from Victor Moses and Diafra Sakho helped West Ham to triumph by the same margin.
The result followed similarly stirring triumphs at Arsenal and Liverpool this season and lifted Slaven Bilic's side up to second in the table, three points behind City.
"We knew we were going to come up against it. They hadn't conceded a [Premier League] goal," Noble told reporters afterwards, as quoted by BBC Sport.
"We watched the Juventus game and took some belief from that. We were nervy at the end but we managed to hold on."
Kevin De Bryune pulled a goal back for City on the stroke of half-time but they could not find a way through again as West Ham stood firm in the face of relentless pressure.
"There are some tired heroes in our dressing room," Noble said.
"We went into the season with a new manager, staff and players and we are slowly gelling together. We knew we had enough to get results like this."
The likes of Moses, Dimitri Payet and Manuel Lanzini have already produced star turns since being brought in in by Bilic over the close season, leading the long-serving Noble to describe his own role in West Ham's early season success with deprecating understatement.
"[Former West Ham striker] Bobby Zamora always used to say to me to get it and give it to the good players," he added. "That makes life easier for myself."
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