Eoin Morgan was cleared to lead England in their World Cup clash with Afghanistan, but Jason Roy admitted his return from a torn hamstring represented a "grey area".
Both players limped out of the comfortable victory over the West Indies last week, but Morgan recovered sufficiently from a painful back spasm to take the field at Old Trafford on Tuesday.
His first act was to win the toss and bat first.
Roy had already been ruled out of the game, as well as Friday's fixture against Sri Lanka and faces an uncertain rehabilitation period.
Speaking on Sky Sports, the Surrey opener reaffirmed his hopes of returning against Australia on June 25 but admitted there was an element of uncertainty given the nature of the injury in his left hamstring.
"(I'm) targeting Australia but we'll see how this week goes," he said.
"It all depends on this week. If this week goes to plan then maybe, but who knows? There's a lot of grey area with hamstrings unfortunately."
England made two changes to the side which beat the West Indies and Bangladesh, James Vince replacing Roy as the head of the innings and spin bowling all-rounder Moeen Ali returning in the place of seamer Liam Plunkett.
