Paceman Gus Atkinson Adds to the English team's Fitness Concerns.
'Significant concern' for the English camp after Atkinson leaves the field due to a hamstring issue.
Gus Atkinson increased the injury concerns plaguing England upon exiting the playing area during Saturday's play of the fourth Ashes Test against Australia.
The pace bowler experienced discomfort in his left hamstring immediately following a delivery in his spell during the morning session.
The touring camp stated the 27-year-old reported "discomfort" and was to take time off the field in order to be assessed "in the coming hours".
The concluding match of the series at the SCG begins on Sunday, 4 January.
England have previously lost key quicks one seamer with a knee problem and another paceman because of a side injury on the current trip.
A replacement bowler was added to the party to provide backup.
The seamer had a tough time early in the series, managing only three wickets.
He was left out from the previous Test, only to be brought back for the Melbourne Test as Archer's replacement.
The county bowler showed better form in Melbourne, bagging two scalps in Australia's first innings, before adding 28 while batting among just a trio of English batsmen to get into double digits.
After bowling one over in Australia's second innings, he returned on Saturday morning and had nightwatchman taken by the wicketkeeper.
However, on the final ball of the fifth over, he delivered a slower ball to the batsman and suddenly grabbed for his hamstring.
Gus Atkinson returned to the side for the Boxing Day Test after being left out the Adelaide game.
