Amended Tour rules state that should two members of a team, staff or riders, test positive for COVID-19, the whole outfit will be kicked out of the race.
Testing will begin on Monday (AEST) and be completed on Tuesday, with approximately 650 people in the bubble to test.
Organisers and the International Cycling Union (UCI) are expected to issue a statement tomorrow before the start of Stage 10.
According to Belga, Tour officials will perform follow-up analysis on any positives to confirm the first result before taking action.
The Polymerase Chain Reaction (PCR) tests return results in two hours, which could see riders still start stage 10 even if they have to be retested.
"We're crossing our fingers,” Cofidis team manager Cedric Vasseur said.
"We took all the procedure to avoid being caught by COVID.
“Even if we are confident, we cannot be 100% sure that nobody will be infected. In any case, if somebody tests positive for COVID, they will be out of the Tour."
Team UAE Emirates sports director Allan Peiper was confident his team had done everything to avoid being infected.
"It’s part and parcel of this Tour,” Peiper said.
"There is no anxiety. We’re in our bubble, we’re safe, we follow the rules and we do what we’re meant to do, and we see nobody else. There won’t be an infection in our group if we follow the rules. I don’t see a problem there."
Riders, however, have expressed concerns that spectators were not being cautious enough, with some of them running alongside the peloton without wearing masks.
"The last few kilometres was like the (Col de) Peyresourde of always but the coronavirus is here and we want the Tour to get to Paris," Tom Dumoulin said after the eighth stage on Sunday (AEST).
The professional riders' association (CPA) issued a statement over the weekend asking all fans to wear masks.