The father of Heung-min Son says the Tottenham striker is NOT world class and must work harder.

Son was the joint winner of last season's Golden Boot after scoring a brace in Tottenham's comprehensive win at Norwich City to take his goal tally to 23.

Son Woong-jung, speaking to CGTN, said: "He [Son] must work harder and make more progress. If he is satisfied with what he has achieved now, crisis is on the way.

"He must always try to do better to stay in the best form, don't you think? Instead of being happy to stay where he is, I always want him to be 10 percent better."

Son Woong-jung went on to hint at a possible transfer for the striker - saying: "He [Son] must be able to play a solid role in one of the world's top clubs.

"That's when he will become a world class player. Like I said before, he must do 10 percent better on every front to reach that goal."

Son Woong-jung also spoke about the striker's goal-scoring prowess and warned he may not find the same form next season.

The striker's father said: "He [Son] scored a lot of goals this year, but it doesn't mean he will do the same next year.

"Only those who stay ready can survive the difficulties. He must face everything with a cautious mind and can't afford to be too proud."