Bayer Leverkusen head coach Roger Schmidt says he is disappointed by the timing of Son Heung-min's likely departure for Tottenham but does not begrudge the South Korea international seeking a move to the Premier League.

Leverkusen's sporting director Rudi Voller has confirmed the 23-year-old forward, who missed his team's 3-0 win in the second leg of their UEFA Champions League play-off at home to Lazio on Wednesday, has undergone a medical at Spurs.

Mauricio Pochettino's north London side have reportedly submitted a bid of €30million for the former Hamburg man, who has made 44 appearances for his country's senior national team.

Speaking after guiding his side into the group stage of the Champions League courtesy of a 3-1 aggregate victory, Schmidt described Son's desire to move on as inevitable, although he is far from happy at the prospect of losing a key player so early in the new season, particularly given the transfer window is set to slam shut on Tuesday.

"I think it's a sad story," he said.

"I can certainly understand that a player thinks about his career and would like to change at the right time. This is absolutely legitimate and ok. This is football business.

"But he was integrated and settled in this team very well, emotionally too, I would have wished that this story would finished another way."

Voller meanwhile attributed Son's absence from the winning team at the BayArena to illness and insisted any potential transfer is yet to be finalised, with the former Germany international holding out hope of retaining a prized asset.

"There is a request and there are talks. But nothing is done," he said.

"Son would not have played today anyway, he was sick at the weekend already. At this moment he is our player. I saw many medicals in this business where there was no deal afterwards."

Leverkusen, who will learn their Champions League group-stage opponents when the draw for the next stage is made on Thursday, are away to title-holders Bayern Munich in the Bundesliga on Saturday, while Son's suitors Spurs host Everton later the same day in the Premier League.