Harry Kane failed to report for Tottenham training on Monday morning as he attempts to force a move away from the Spurs, according to ESPN's James Olley.
The 28-year-old was due to report for COVID-19 testing and routine bloodwork after a break following England's Euro 2020 loss to Italy.
Kane has spent the last nine seasons with Tottenham, scoring 162 goals in 220 starts. It was reported that he would demand a transfer if the Spurs missed the Champions League in 2020-21, which they did.
According to Olley, Manchester City are the front-runners for Kane and are hopeful of completing a deal. The English forward became the club's top target this summer after losing Sergio Aguero to Barcelona.
Fabrizio Romano of Sky Sports reported last month that Man City had made a £100 million offer for Kane, and Tottenham had "no intention to accept" that offer.
In addition to Manchester City, Chelsea and Manchester United are also monitoring Kane's situation with Tottenham, according to Olley.
Kane has a strong desire to play in the Champions League. Playing for Man City or Man United would give him that opportunity.