Harry Kane, a transfer target for Manchester City, did not return to the Tottenham training ground as expected on Monday morning amid speculation over his future.
The striker was scheduled to have coronavirus testing on Monday before starting training on Tuesday.
Kane has had a three-week break after helping England reach the Euro 2020 final.
Spurs have offered no explanation for why the 28-year-old did not turn up.
It is understood Kane felt he had a gentleman’s agreement with Tottenham chairman Daniel Levy that he could leave the club this summer.
A pre-Euro 2020 move did not materialise as he hoped, but Manchester City remain keen on signing the England captain.
Kane’s international’s team-mate Jack Grealish is also a target for City, who have a made a £100m bid for the Aston Villa midfielder, and he turned up for pre-season training with the Midlands club on Monday.