Portsmouth coaches Paul Groves and David Coles have quit the club to team back up with former Pompey manager Avram Grant at West Ham.
Ian Woan and Guy Whittingham will assist Portsmouth manager Steve Cotterill in first-team coaching duties while a replacement for Groves is considered and John Keeley will step up from Pompey's academy to replace Coles as first-team goalkeeping coach.
Portsmouth chief executive David Lampitt said: "We are sorry to lose both Paul and David to West Ham, but understand the offer to continue working in the Premier League was difficult to refuse.
"I would personally like to thank them both for the excellent jobs they have done at the club and wish them well for the future."
On Keeley's appointment, Cotterill added: "John has worked well in the academy and is looking for a step up. We're more than happy to promote from within.
"At the moment I'm working with Guy and Ian and just want to see the dynamics of the group before appointing anybody else."