Exeter and England wing Jack Nowell is facing between four to eight weeks on the sidelines with an injury around his cheek and eye socket.
Rob Baxter told reporters on Wednesday that the international suffered "a couple of fractures" but did not offer a return date for the player.
"Jack has got a couple of fractures around the top of his cheek and his eye socket. "At this stage, it is looking likely he'll require an operation to settle it down. Until the surgeon moves in and does some more investigation, that’s about as far as I can tell you," he said.
"Depending on when the operation happens, if it is definitely required, which is looking likely, and the severity of the injury, that will then decide whether there is no way back for the autumn internationals.
"It is still a little early to write him off for the whole of the autumn internationals, but that is something we will assess in the next week or so."
Ahead of their Champions Cup opener against Glasgow, Baxter added: "It is always a blow when you lose good players, but that’s why you put a squad of people together.
"I am disappointed for him personally. He is in good form, starting this season really well for us, and obviously he wanted to have a couple of big rounds in the European Champions Cup to get himself right in the frame for England.
"That, unfortunately, has been damaged now with a pretty innocuous and unfortunate injury. Now, he is going to be held back for the next six to eight weeks.
"It is in and around his eye. We are not anticipating any issues with his vision but obviously there are optical nerves and facial nerves around that area that an operation will disturb. Those things will take a little while to settle as well.
"I don’t want to say the wrong thing. Until we have fully got right into the crux of what is going on there…we are still waiting to see the consultant. I think six weeks from the time of injury is a figure that we’ve had bandied around. There is the potential for it to be four weeks, there is the potential for it to be eight weeks."