Pakistan and Zimbabwe's limited overs series in August is expected to become a tri-series with the West Indies set to join the party as competition to qualify for the 2017 Champions Trophy hots up.The involvement of the West Indies would essentially make the series a shoot-out between the Caribbean team and Pakistan for the eighth and final spot in the Champions Trophy, which will be hosted in England.Pakistan are due to tour the African nation in a reciprocal arrangement with Zimbabwe Cricket (ZC), who sent a team to Pakistan in May to play two T20Is and three one-day internationals, the first Test-playing nation to tour Pakistan in six years.However, it is understood West Indies are close to agreeing terms to make the series a three-way format. Currently the Caribbean team do not have any ODIs scheduled before September 30, the cut-off date for teams to qualify for ICC Champions Trophy 2017 in England and Wales.