England could face South Africa in June without captain Dylan Hartley as the Northampton hooker continues to suffer concussion symptoms.
The England skipper, 32, has not played since Ireland secured a Six Nations Grand Slam with victory at Twickenham on March 17.
Northampton do not have a match this weekend, allowing Hartley an extended period of rest. However, should his symptoms not improve then his place on England's three-Test tour of South Africa would be in serious doubt.
Hartley has dealt with concussions before, and has spoken of his concerns were he to suffer another head injury.
Two years ago the England hooker missed a combined 14 weeks after he suffered two concussions during the season. "If I got another one now, I would be worried," he said on his return. "I would probably start looking at other careers -- or a long lay-off."
Were Hartley to be ruled out of England's tour then there is a possibility that Chris Robshaw could regain the armband.
Owen Farrell is his country's vice-captain but is expected to be given the summer off following his exertions with the British & Irish Lions in 2017.
Robshaw has shared the responsibility in the past with George Ford on occasions when Hartley and Farrell have been unavailable.