England beat Australia 45-22 at Twickenham, but the win came at a cost for Steve Borthwick.
Immanuel Feyi-Waboso and Seb Atkinson both picked up injuries during Sunday's Nations Championship clash.
Feyi-Waboso went off after a controversial tackle by Australia's Angus Bell, who was shown a yellow card.
The Exeter Chiefs winger was later seen wearing a protective boot, sparking fears over his fitness.
Atkinson also left the pitch with England's medical staff, giving Borthwick another injury worry.
England have yet to confirm how serious either injury is.
The Red Rose impressed in attack, as shown in RUCK's player ratings against Australia.
But the injuries took some of the shine off a fine win.
Immanuel Feyi-Waboso injury
England face an anxious wait after Immanuel Feyi-Waboso suffered an ankle injury against Australia.
The Exeter Chiefs winger went off following a controversial tackle by Angus Bell, who was shown a yellow card.
Feyi-Waboso was later seen wearing a protective boot, sparking fears over his fitness.
Speaking after the match, Steve Borthwick said the injury needs further checks.
England are still unsure how serious it is.
The 23-year-old now faces a nervous wait ahead of Saturday's clash with Japan.
Seb Atkinson injury
There was better news for Seb Atkinson, who hurt his hip during the win.
The Gloucester centre left the pitch with England's medical staff.
However, Borthwick suggested the injury was not too serious.
Atkinson is sore and bruised, but the problem is not expected to keep him out for long.
He could miss next weekend's clash with Japan, although it is too early to say.
Steve Borthwick faces selection headache
The injuries have given Borthwick more problems ahead of England's next two games.
The England boss is already missing several key players, including Alex Mitchell.
As RUCK previously reported, the scrum-half will miss the autumn campaign with a hamstring injury.
Meanwhile, Tom Curry's return date remains unclear after he hurt his hip in training.
England face Japan on Saturday, 14 November, before taking on New Zealand a week later.
Borthwick will now hope for good news on both players.
Additional reporting by Charlie Elliott at Twickenham.
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