Joe Launchbury suffered a head injury during Wasps' Premiership victory over Worcester Warriors on Sunday to leave England head coach Eddie Jones with another concern ahead of the Six Nations.
The lock will undergo tests after coming off in the second half as Wasps snatched a 32-22 victory at the Ricoh Arena courtesy of late tries from Frank Halai and Sailosi Tagicakibau.
England start their Six Nations campaign against Scotland at Murrayfield on February 6 and Jones must wait to discover whether Launchbury will be fit enough to feature in what is the first game in charge for Stuart Lancaster's successor.
Wasps director of rugby Dai Young said: "He's taken a nasty head knock but he's up and about. He's talking and appears to be fine but will have to go through the relevant protocols.
"It could take one or six weeks, it's impossible to tell at this stage."
Jones is due to name his first 33-man Elite Player Squad on Wednesday and has already been dealt a blow with the loss of Jonny May, while George Kruis, Jack Nowell and Dylan Hartley are also injury concerns.