Avram Grant saw his West Ham side squeeze through to an FA Cup fifth-round meeting with Burnley as the Hammers claimed they had signed Robbie Keane from Tottenham.
Keane was at Upton Park to see striker Victor Obinna score a hat-trick as West Ham beat Nottingham Forest 3-2.
And Grant insisted Keane was just the character the Hammers need in their fight against relegation, saying: "He (Keane) is not just a good player, he is a good character that we need in the next 14 games."
West Ham are thought to have agreed a deal which takes Keane initially on loan until the end of the season with a view to making a Â£6million deal permanent for the next three years. It could depend on whether West Ham escape relegation.
West Ham co-owner David Gold told BBC Sport: "We're delighted to sign a world-class striker.
"Tottenham chairman Daniel Levy drives a hard bargain but we've got our man."
Grant insisted he also intends to add another signing to the reinforcements he has already made to his squad before Monday's 11pm deadline.
Gary O'Neil, Demba Ba and Wayne Bridge have all arrived at West Ham during the transfer window.