A BBC statement said: “Tom Fletcher and Amy Dowden have tested positive for Covid-19.
“The pair are now self-isolating separately following the latest Government guidelines.
“While they will both miss Saturday’s live show, Strictly Come Dancing protocols mean that, all being well, they will return the following week.”
Strictly Come Dancing has seen its television audience grow to almost eight million viewers, according to overnight ratings.
The BBC said an average audience of 7.9 million tuned in on Saturday night to watch the couples compete in front of the judges for the first time.
The BBC One celebrity dancing competition was watched by a peak audience of 8.4 million and had a 47.9% audience share.
Last week’s launch programme was watched by an average audience of 7 million, with a peak of 7.3 million and 44.7% audience share.