West Ham are showing interest in Chile international defender Guillermo Maripan but face competition from Roma.
The 6ft 4ins defender, who plays for Alaves in Spain's La Liga, is well liked by Hammers boss Manuel Pellegrini and was a target for his compatriot in January.
Roma, however, have held talks in recent weeks with Alaves and have moved into pole position.
Maripan has 13 international caps and is a ball-playing centre back who has been likened in style to Barcelona's Gerard Pique.
He has been a key figure during a successful season for Alaves who are currently fifth in the table and pushing for European qualification.
West Ham have had a number of issues at centre back, mainly because of injuries.
Pellegrini wants to bolster his options but the club face a tough challenge to fend off Roma.
