Fabregas suffered a broken leg playing in the first leg of Arsenal's Champions League quarter-final tie against Barcelona, ruling the club captain out of the Gunners' title chase.
Tough break: Fabregas was injured in this challenge by Puyol
But Lewin had good news for Spain fans concerned about the influential midfielder.
'Cesc is doing well,' he told the club's website.
'He is likely to be out for the rest of the season with a hairline crack of his fibula. If everything goes well he will comfortably make the World Cup and we will be constantly monitoring him.'
Lewin also reiterated that the injury was suffered during the Barcelona match, dismissing earlier reports that Fabregas was at less than 100% prior to kick-off.
'The injury was certainly as a result of the tackle by Carles Puyol at the end of the Barcelona game,' he said.
'There were some ill-informed media reports that the fracture was sustained before the Barcelona game and those reports, put simply, were untrue.
'He suffered heavy bruising in the Birmingham City game but to suggest that someone can run around for 85 minutes against Barcelona with a fractured fibula is just farcical.
'We examined Cesc after the Birmingham game and he had suffered heavy bruising. The x-rays confirmed that there was no fracture. At the end of the Barcelona match, following the challenge from Puyol, Cesc had an x-ray to determine the damage.
Road to recovery: Fabregas suffered a hairline crack of his fibula but is expected to be back for the World Cup
'It showed a hairline crack, which unfortunately means Cesc will miss the rest of the season.'
Arsenal have been hit by several injuries this season, but Lewin revealed that forward Robin van Persie is close to a return, along with Johan Djourou and Kieran Gibbs.
'Johan Djourou had a difficult problem with the cartilage in his knee joint,' he said.
'He has made virtually a full recovery and we expect him to train fully with the squad within the next fortnight, as will Kieran Gibbs. They have both made full recoveries from what could have been career-threatening injuries.
'Robin will be joining the squad for full training imminently. That is a big boost for the club and to see Johan and Kieran training with the team in the next fortnight will give everyone a big lift.'
Aaron Ramsey, who suffered a broken leg at Stoke, will have to wait until early next season to make his own return.
'Aaron will make a full recovery,' Lewin said. 'Other footballers have suffered a similar injury. The surgery went very well and the early signs are very good.
'We don't expect Aaron to return until the early autumn. He has some metalwork in there and that provides the stability for the fracture.
'The specialists have encouraged him to walk and this weight-bearing will aid the fracture healing. It's early days but the signs are very good.'
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