If Dawson's injury is serious, it could throw England's preparations for their clash with the Springboks into disarray, especially after fellow scrum-half Kyran Bracken pulled out of the Georgia game during the pre-match warm-up with a back spasm.
Gloucester star Andy Gomarsall stepped up to replace Bracken on the bench and came on when Dawson left the field against Georgia in the 36th minute. Now Gomarsall finds himself as England's only fully-fit No.9.
In the meantime, England coach Clive Woodward has taken no chances, with Bath's Martyn Wood flying to Australia as cover at halfback.
Leicester jack-of-all-traders Austin Healey is out of the equation after suffering a calf strain, which saw him withdraw from the Tigers' Zurich Premiership game against Gloucester at the weekend.
Woodward, however, was at pains to stress that Wood was merely making the trip as a precaution at this stage.
"We will monitor the progress of Matt Dawson and Kyran Bracken every 24 hours before making a final decision on their availability for the South Africa game up to, and including, Thursday," the England coach told Britain's Press Association.
"Martyn is not joining the squad. However, if he is required, then he would do a good job."
* Meanwhile, Wood's Bath team-mate, powerhouse centre Mike Tindall, who left the field at the same time as Dawson, picked up a calf strain against the Georgians.
Tindall will also be monitored this week after being rushed back to the England team's hotel to begin treatment ahead of the SA game.
For all the criticism that he has had to endure, Tindall remains a key man for England, and his possible loss would also be a massive blow to England's Rugby World Cup hopes.
The other specialist centre in the squad is London Wasps' Stuart Abbott, while another Bath man, veteran Mike Catt, has played many Tests in the England midfield, despite having been named at fly-half in the current squad.