Montenegro joined West Ham in August 2011 after signing a season-long loan contract saying, “I am very excited to come here and play in England, especially for a club like West Ham. I am hoping to get a chance to show the fans what I can do”. Montenegro’s debut and only game came on 8th January 2012 in a 1–0 FA Cup third round away defeat to Sheffield Wednesday when he came on as a 78th minute substitute for Gary O’Neil . He never made another appearance and no new contract was agreed at the end of the season so he returned to Paraguay.