Kai Havertz has fired a warning to his club Bayern Leverkusen and in order to make his stand known he reportedly missed the test for pre-season BILD reports.
The 23-year-old completed mandatory COVID-19 tests on Friday and Saturday.
But Havertz was not involved in the pre-season fitness tests on Sunday.
Leverkusen begin their preparations ahead of the new season with an open training session on Monday.
Although a number of top clubs were linked with Havertz this summer, the playmaker has his heart set on Stamford Bridge.
The Blues are close to agreeing an initial £70m deal with £15m in add-ons.
Havertz will join the likes of Hakim Ziyech, Timo Werner, Ben Chilwell and Thiago Silva, who have all completed their transfers to Chelsea ahead of the new season.