The timing of the injury is a real blow for the forward, who has been in impressive form and scored a hat-trick in England's 4-0 victory against Bulgaria at Wembley in the opening qualifier last Friday.
The loss of the forward is another blow to Gunners manager Arsene Wenger, who has been hit by the news that Netherlands striker Robin van Persie will be sidelined until at least the middle of October because of an ankle problem.
If the 26-year-old, five-times capped forward does decide to move it will be blow to Rodney Parade outfit who have performed well in recent weeks despite recording two losses in a row.
The signing will be a blow to Carlisle boss Gregg Abbott, who revealed to BBC Radio Cumbria he had been in talks with the forward about a move to Brunton Park.