Gloucester director of rugby Nigel Davies conceded Billy Twelvetrees' ankle injury was 'not great' after the England star limped off against London Irish.
The news will not have been greeted well by England head coach Stuart Lancaster ahead of the tour to New Zealand.
Twelvetrees has been used as a fly-half by Gloucester over the last few months but was England's premier inside centre during the Six Nations, forming a strong partnership with Luther Burrell.
"It is an ankle problem and, with a lot of these things when a player is injured, it is very difficult to give a formal assessment," said Davies.
"But what we will do is monitor the situation in the next 48 hours and, within that period, he will have a scan which will identify the extent of the problem.
"Until we have a clearer picture, we cannot say how serious it is.
"Billy is a committed player and, for him to come off - because there was a lot of emotion around the game - obviously says quite a bit about the injury.
"But like all things, we just have to wait and see for a couple of days."