The star-striker is at hospital having x-rays and scans to reveal the full extent of the injury but he now looks to be a major doubt for the Hammers' start to the new Premiership season.
Ashton had been set to start against Greece but it now looks likely to miss a number of months if a break to the ankle is revealed.
England manager Steve McClaren said, “The injury to Dean has really clouded the morning. It's always disappointing when a young player is injured and yes, Dean would have started tomorrow.
“We did some work with him yesterday and were going to work on him again today. These things happen in football, though, it's very disappointing and we are all very sorry to see it happen.”