The Cameroon midfielder has made just four appearances since his £1.3m move from Manchester United in January. He has failed to impress, however, and was left out of the side for the 2-0 win against Middlesbrough a fortnight ago.
David O'Leary was typically sanguine about the blow. "Eric has picked up this hamstring strain in training and I'd imagine it'll be something like six weeks," he said, looking not unlike a lonesome Moomin. "I bought Eric more with a view to next season. I really feel he will need a good pre-season under his belt with the way that we play. He hasn't played much and we need to get him up to speed."