The former Spain and Real Madrid coach was cut into 1/2 sack race favouritism after Tuesday night’s 3-1 defeat at Leicester, the latest in a string of poor performances under the Spaniard.
Most firms then chose to suspend the book on the next Premier League manager to leave their post after reports filtered out of West Ham considering their options.
Chairman David Sullivan usually affords his managers time to turn things around, but alarm bells are ringing among the club’s hierarchy.
The board is expected to discuss this week whether Lopetegui will still be in charge for West Ham’s next match, at home to his former club Wolves on Monday.
After that, the Hammers face fixtures against Bournemouth, Brighton and Southampton.
If the 58-year-old clings on to his role, those four matches are likely to shape his future.
The concern among the board is that if the Hammers do not pick up enough points from those games, then they could be in a relegation scrap and any new manager would have to take charge of a home match against Liverpool followed by trips to Manchester City and Aston Villa.
West Ham brought in former Real Madrid and Spain boss Lopetegui to replace David Moyes, who left at the end of last season.
It was felt the team has gone stale under Moyes over the season which followed their Europa Conference League success.
But despite a £130million investment in new players in the summer, performances and results have shown no significant improvement.
The Hammers are currently 14th, six points above the drop zone, having won just four of their 14 matches and conceded 27 goals.
Former Brighton and Chelsea boss Graham Potter is understood to head a shortlist of potential candidates to replace Lopetegui.
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