Revealed: The clause that has kept Son Heung-min at Tottenham this summer despite doubts over long-term future as South Korea pre-season tour looms

According to Telegraph Sport, Son's presence in Tottenham's pre-season game against Newcastle United in Seoul next month is very important to the north London club. If the forward is not part of Spurs' touring squad, they will miss out on as much as '75 per cent of their fee' for playing in the South Korean city - with that amount being halved if he travels but does not play in the game.

Son looked like he could leave Tottenham this summer after their Europa League success, with the 33-year-old linked with a Major League Soccer switch. The report adds that barring a last-minute injury, Son is likely to travel to Asia and play in Seoul on August 3 to secure Spurs a big cash boost and not to let down his army of fans. Moreover, the key player clause means that it was 'virtually impossible' for Tottenham to consider selling the veteran before this pre-season tour.

Son, whose Spurs contract runs until 2026, joined Tottenham in 2015 from Bayer Leverkusen and has since scored 173 goals and added 101 assists in 454 appearances in all competitions. It remains to be seen if he will add to that next term.

Son played a big part in the club ending their 17-year wait for a trophy and the South Korean may add to his legacy with another season at the club. Manager Thomas Frank appears to want him to stay but whether he does is up in the air.