West Ham joint-chairman David Gold was left red-faced after tweeting a picture of Angelo Ogbonna in a welcome message intended for new signing Pedro Obiang.
Obiang became the club's latest signing of the close-season on Wednesday, with the club having appointed new manager Slaven Bilic a day earlier.
However, in attempting to welcome the Spanish striker, Gold mistakenly Tweeted a picture of Italy international Ogbonna.
After receiving a raft of replies from followers pointing out his error, the Tweet in question was swiftly deleted and replaced by one with Obiang in shot.
"I am delighted to announce the signing of 23-year-old midfield [sic] Pedro Obiang from Sampdoria. Pedro, welcome," Gold later posted.
"I've just spoke to Pedro and he sounded very excited to be here. He promised me that he'd learn to sing club anthem Bubbles in less than a month!"