West Ham and Southampton maintained their impressive starts to the English Premier League football season after beating champions Manchester City and Stoke respectively.
The Hammers beat holders Manchester City 2-1, while Saints edged Stoke City 1-0.
Manchester City lost at West Ham through goals from Morgan Amalfitano and Diafra Sakho.
Elsewhere Arsenal won 2-0 at Sunderland to climb to fifth, while Liverpool were held to a goalless draw at home by Hull City.
Swansea City defeated Leicester City 2-0 and West Bromwich Albion fought back from 2-0 down to draw 2-2 at home to Crystal Palace.
West Ham did not have it easy against Manchester City who dominated possession but hit the bar twice through Yaya Toure and only scored once through David Silva.
Frenchman Amalfitano put the Hammers ahead with a tap-in after a brilliant low spinning cross from Enner Valencia after 21 minutes.
Senegalese Sakho became the first West Ham player to score in six successive Premier League games when he made it 2-0 with a goal given after goalline technology showed his header had crossed the line in the 75th.
Silva pulled one back for City with a great solo effort as he weaved through the defence two minutes later.
"It wasn't a lucky victory by any stretch of the imagination today because our commitment and desire to play against the big boys and the present league champions was there for all to see," said West Ham manager Sam Allardyce.
"After David Silva scored their outstanding goal, for me it was about the squad's determination to make sure of what is a famous victory for us."
City manager Manuel Pellegrini denied he was under any more pressure after his side also let slip a 2-0 lead against CSKA Moscow to draw 2-2 in the Champions League in midweek.