West Ham's official shirt sponsors, Betway, have apologised for criticising Michail Antonio on social media on Monday night.
Antonio gave away a penalty as the Hammers opened their 2016/17 Premier League campaign with a 2-1 defeat to Chelsea at Stamford Bridge on Monday Night Football.
Eden Hazard converted from 12-yards and, though James Collins restored parity with less than 15 minutes to go, Diego Costa netted the home side's winner in the 89th minute.
Antonio, whose usual position is as a right winger, has been utilised as a right-back by manager Slaven Bilic since the end of last season, despite a certain section of the club's support calling for him to be restored to an attacking position.
Following his error last night, Betway tweeted from their official Twitter account: "Antonio has been an accident waiting to happen in defence… West Ham fans will hope that's the end of the experiment."
Sky sources understand West Ham and Betway held a conference call on Tuesday to discuss the tweet.
Betway have told Sky Sports News HQ they have a team of passionate writers who provide impartial opinion across all sports, but acknowledge this particular tweet was inappropriate in light of the company's relationship with West Ham.