James Ward-Prowse had two assists on his West Ham debut to help his new team beat Chelsea 3-1 in the Premier League on Sunday despite playing with 10 men for 30 minutes, leaving Mauricio Pochettino still looking for a first win as Blues manager.
Ward-Prowse set up the first two West Ham goals to upstage Moises Caicedo, who gave away a clumsy penalty for the third goal in injury time after coming on as a second-half substitute for his first Chelsea appearance since his record-breaking $146 million move from Brighton.
Ward-Prowse, who joined from relegated Southampton this week, delivered a perfect corner that was headed in by Nayef Aguerd to give West Ham the lead in the seventh minute.
Carney Chukwuemeka equalized for Chelsea in the 28th and Enzo Fernandez - who cost Chelsea about $130 million last season - then missed a penalty for the Blues just before the halftime break.
West Ham retook the lead when Ward-Prowse played a ball over the top for Michail Antonio to run onto and the striker beat Robert Sanchez with a shot from the edge of the area in the 53rd.
Aguerd then earned a second booking for a badly mistimed challenge in the 67th, but Chelsea was unable to take advantage as its lack of attacking options again made itself evident.
Instead, Caicedo tripped Emerson in the area to give away a penalty that Lucas Paqueta calmly converted in the fifth minute of injury time.
Both teams had opened the season with draws last weekend, though Chelsea had looked impressive in a 1-1 stalemate against Liverpool at home.
Since that game, Chelsea completed the signings of both Caicedo and fellow midfielder Romeo Lavia in the hopes of becoming more defensively solid, but the latter was not even on the bench. And for Caicedo, it was a debut to forget.