West Ham are confident that Portsmouth defender Tal Ben Haim will not be the last of the summer arrivals at Upton Park.
Ben Haim, 28, finally completed his protracted move to West Ham on a five-month loan deal amid reported concerns that he has a groin problem.
The Israel international is manager Avram Grant's fourth signing since he took over at West Ham, following the arrival of German midfielder Thomas Hitzlsperger, Mexican winger Pablo Barrera and French forward Frederic Piquionne.
Grant, who has introduced a new 4-3-3 system at West Ham for the new season, is still looking to strengthen his squad further ahead of the new season - possibly by the end of the week.
A club statement read: "Club officials have stepped up their bid to secure a fifth signing and hope to have the deal finalised within the next 72 hours.
"The potential recruit is a young international, who represented his country to distinction at the 2010 FIFA World Cup."
West Ham have fielded Germany Under-21 international Anis Ben-Hatira and Argentina's Milton Caraglio during pre-season, though neither featured against Ipswich at the weekend.
The club have also been linked with Serbian winger Miralem Sulejmani, who played under West Ham's new assistant manager Zeljko Petrovic at Ajax.
Ben Haim's move to Upton Park reunites him with Grant, who he has played under for Chelsea, Portsmouth and the Israel national team.
He has also played for Bolton, Sunderland and Manchester City in a nomadic Barclays Premier League career.