West Ham co-owner David Sullivan has visited the club's training ground as Slaven Bilic's future grows increasingly doubtful, with Sky Sports reporter Kaveh Solhekol claiming that Sullivan's appearance at the ground is 'very unusual.'
Bilic's job is believed to be under serious threat after his side's 3-0 defeat against Newcastle on Saturday.
The Hammers had lost their two previous Premier League outings against Manchester United and Southampton, and are yet to earn a point after three games.
West Ham have conceded ten goals and scored just two in a difficult opening to the season, leading to early speculation that Bilic could be the first manager to lose his job.
The Hammers have been unable to play at home this month due to the world athletics championships at the London Stadium.
The London club's summer spending - nearly £40m spent on the likes of Marko Arnautovic and Javier Hernandez - has led to added expectation after last season's mid-table finish.
With Bilic's position now in doubt, Newcastle boss Rafa Benitez has been made the favourite to replace the Croatian coach. Former Manchester City manager Roberto Mancini has also been linked with the job, as have Simone Inzaghi and Slavisa Jokanovic.
Bilic admitted after the defeat against Newcastle that the scoreline and performance from his side was "worrying".
"This is different, this is worrying, but like for every club, it has its ups and downs and nobody will take us out of this situation but ourselves," he told the BBC.
"Look, I am the manager, it's my job to be confident and to believe in good and bad times. Even when the times are bad, then you see the importance of the job more than in the good times. I haven't changed in that."