Arsenal captain Thomas Vermaelen will miss the start of the season with a back injury that will rule him out for three months.
The Belgian international did not travel with the rest of the squad to Vietnam, where Arsene Wenger's side won 7-1 in a pre-season friendly against the national side.
He stayed in London to recieve treatment, but scans have shown the stress fracture in his lower back to be more serious than first thought.
Vermaelen joined Arsenal from Ajax in 2009 for £10m.