The Welshman had been in fine form this pre-season and had been looking forward to forming a partnership with Dean Ashton before picking up the injury in West Ham's friendly against
He told the official site, "I have been fit and well throughout the pre-season so this was not anything that had affected me before at all. It is just one of those things that happened in the match and now I will be just concentrating on getting through it and coming back strong and well to do my best for West Ham.
"I am out for a month and so it is gutting for me not to be able to start the season, especially as I have had a great pre-season and worked really hard.
"I have been looking forward to this season with West Ham so much, one of the most I have looked forward to. I wanted to hit the ground running and make an immediate impact.
"I have done this in pre-season, and was looking to carry this into the start of the new season, but I will just have to wait a bit now to do this. But I am making sure I am working as hard as possible in getting over the injury and will come back better and stronger than before to play my part in the team."