The Scots have postponed naming their team for the match in Leicester and have been forced to call up five new players to the squad.
Murrayfield chiefs insist the match is “still scheduled to go ahead as planned”, but interim head coach Mike Blair has had to rip up his original game plan for the first part of Scotland’s summer programme.
The match against England’s second-string at Welford Road will be followed by full Test matches in Romania and Georgia in July.
Blair, who is standing in for Gregor Townsend while he is on duty with the British and Irish Lions, had named a 37-man squad for the match with England, which was then due to be trimmed back to 29 ahead of the tour to eastern Europe. However, the coach has had to think on his feet.
As a result of the quarantine restrictions, Glasgow Warriors duo Stafford McDowall and D’Arcy Rae, Edinburgh’s George Taylor, Ben Vellacott of Wasps and Saracens forward Callum Hunter-Hill have all been called up to face the Red Rose reserves.
The Scottish Rugby Union, which is not naming the player who tested positive or the eight who are isolating, said in a statement: “Scottish Rugby can confirm a Scotland men’s player has tested positive for Covid-19 while preparing to face England A this weekend.
“The player started self-isolation as per Scottish Government guidelines.
“Subsequent internal contact tracing identified a group of eight potential contacts who are also isolating and as such nine players have been ruled out of Sunday’s A international fixture against England A at Mattioli Woods Welford Road.”
The Scots were due to travel to Leicester on Thursday but the trip was postponed as a precaution while the entire squad and management team were re-tested.
The SRU says no further positive results have been returned from the playing group and Blair will now name his side on Saturday morning.
Of the five players called into the squad only Rae has played for the full national side. The 26-year-old tighthead prop, who has signed for Bath for next season, won a cap as a replacement against Ireland in the 2019 Six Nations Championship.
McDowall, 23, has represented Scotland at both U18 and U20 level and at 6ft 4in and 100kg offers a powerful presence at centre.
Borderer Taylor is another centre who has come through the U18 and U20 national set-ups.
Vellacott, a scrum-half who was courted by England, has agreed a move to Edinburgh for next season. He qualifies for Scotland through his mother and has also played age-group rugby for Scotland.
Hunter-Hill had spells with both Glasgow and Edinburgh before joining Saracens and the lock forward was part of the squad which helped Sarries win promotion back to the English Premiership by beating Ealing in the Championship play-off final last weekend. He is a former Scotland U20 captain.