Winston Reid will miss the visit of Stoke City this weekend as well as the upcoming World Cup Qualifiers against New Caledonia because of injury.
David Moyes' Sunderland crumbled at the death to give West Ham a deserved win at the Olympic Stadium.
Winston Reid turned in Dimitri Payet's set piece past David De Gea for the winner as West Ham beat Manchester United 3-2 to close the Boleyn Ground.
West Ham came through a bruising 120 minutes of football this week to guarantee their place in the fifth round of the FA Cup at the expense of Liverpool. However, the win came at a cost having picked up a number of injuries on the night.
Winston Reid has become the third West Ham player within the last 7-days to be ruled out until 2016. The defender suffered a hamstring strain in training on Wednesday as the Hammers prepared for the visit of Stoke this weekend.
Winston Reid will miss gameweek 10 with a back injury.
WInston Reid has emerged as a doubt for West Ham's match against Sunderland tomorrow.
Winston Reid will miss West Ham's Europa League match against Astra.
Winston Reid has recovered from a hamstring injury and should be included in the gameweek 37 squad.
Winston Reid is once again ruled out with a hamstring injury and it's becoming more and more unlikely he features again this season.
Winston Reid will miss GW35 with a hamstring injury.
Winston Reid is training with the main group again after battling a hamstring injury for a few weeks.
Winston Reid will miss his international duty with New Zealand since he has still not recovered from a hamstring injury.
Winston Reid will be a late fitness check for gameweek 30 but is considered doubtful to play.