The latest round of Premier League coronavirus testing found 18 people had the virus - the highest figure recorded in the league's testing programme.
That figure surpassed the previous highest figure recorded - 16 for 9-15 November - though the percentage of positive cases was lower.
The 18 positives come from 1,479 tests on players and staff between 21 and 27 December, a rate of 1.22%.
The round that produced 16 positives was from 1,207 tests at 1.33%.