Chelsea are extremely active heading towards the transfer deadline, with the Blues having captured Kepa Arrizabalaga and Mateo Kovacic to bolster their squad.
Outgoings are also on the cards, with Thibaut Courtois moving to Real Madrid, and further departures could follow the Belgium international out of Stamford Bridge.
The Guardian states Championship promotion hopefuls Middlesbrough are seeking a deal for Tomas Kalas to bring the 25-year-old defensive outcast to the club on loan for the 2018-19 season.
Kalas signed for Chelsea in 2010 but has earned just two Premier League appearances in his eight years at the club, spending numerous spells away on loan – including the last two seasons with Fulham, winning promotion last year.
The defender has previously spent two spells on Teesside with Middlesbrough, most recently in the 2015-16 season, and Tony Pulis wants to bolster his defensive options with the services of the 25-year-old.
With the Football League’s loan market not closing until the end of August, Middlesbrough have plenty of time to negotiate a deal.