West Ham are poised to break their transfer record to sign Sebastien Haller for a fee that could rise to €50m despite late interest in the Eintracht Frankfurt striker from a rival bidder.

There was concern at West Ham that the 25-year-old’s head would be turned after a last minute attempt to hijack the deal by a club from abroad, believed to be in the Champions League. Despite those late doubts, however, it is understood Manuel Pellegrini’s search for a new striker is likely to end in success.

West Ham reached an agreement with Frankfurt and Haller late on Monday night, at which point they were confident the deal was moving in the right direction. The German club appeared to confirm as much when they tweeted: “Eintracht and West Ham have agreed on the details of the transfer of @HallerSeb. As a result, Haller has approval to complete the medical examination in London. Should this take a positive course, Haller will join the Hammers.”

Die Eintracht und @WestHamUtd haben sich über Transfermodalitäten bzgl. @HallerSeb geeinigt. Infolgedessen hat Haller die Freigabe, um die medizinische Untersuchung in London zu absolvieren. Sollte diese einen positiven Verlauf nehmen, wird sich Haller den „Hammers“ anschließen. pic.twitter.com/RzpMDW5mFI — Eintracht Frankfurt (@Eintracht) July 16, 2019

Haller was on his way to London for a medical at that point, only for the situation to change when West Ham heard that the former France Under-21 international’s agent was talking to another club. The London Stadium club feared their target’s head would be turned and sources close to the deal put the chances of it being completed at 50-50 on Tuesday morning. Sources close to Haller have not been available for comment.

West Ham spent the rest of the day working to complete a deal that will see them pay Frankfurt an initial €45m and €5m in add-ons and Haller eventually had his medical in the afternoon. Barring any last-minute hitches over personal terms West Ham are confident the deal will be completed. Frankfurt are aware of an alternative offer, but they also expect Haller to join.

Pellegrini has been desperate to find a new striker after allowing Marko Arnautovic to join Shanghai SIPG for £22.4m and losing out to Valencia in the race to sign Maxi Gomez. West Ham acted quickly after missing out on Gomez and made their move for Haller last week..

Haller, a 6ft 3in forward, has scored 33 goals in 77 appearances since joining Frankfurt from Utrecht two years ago. He formed a formidable partnership with Luka Jovic, who has left for Real Madrid this summer, and Ante Rebic. Frankfurt reached the semi-finals of the Europa League last season and were unfortunate to lose to Chelsea on penalties.

West Ham, who have already bought the attacking midfielder Pablo Fornals from Villarreal for £24m, were under pressure after selling Arnautovic. Having already allowed Andy Carroll and Lucas Perez to leave, their only senior forwards were Javier Hernandez and Jordan Hugill, who has rejected a move to Wigan after failing to agree personal terms.

Meanwhile West Ham have sold Sam Byram to Norwich City for £750,000. The 25-year-old right back has struggled to make an impact since his move from Leeds United in January 2016.