Ilkay Gundogan
Ilkay Gundogan's future uncertain after Dortmund admitted they will sellGetty

Borussia Dortmund chief executive Hans Joachim Watzke expects two major players to leave the club this summer.

Manchester United remain heavily linked with two widely expected to move on from the Westfalenstadion in midfielder Ilkay Gundogan and captain Mats Hummels.

With former skipper Sebastian Kehl retiring at the end of the season and speculation also growing over the future of Neven Subotic, Dortmund could face another overhaul of their squad to ensure they are competitive for next season's Bundesliga campaign. But Watzke insists there will be no mass exodus in the coming months.

"There will be no major overhaul," Watzke told Reuters. "Last year one player left [Robert Lewandowski who joined Bayern Munich], this year it is probably two.

"Everything else is still open. So yes, there will be change not bot a complete overhaul of the team. As for any of the other cases, I will not talk about names."

Gundogan was reportedly the subject of a £21m bid from Old Trafford in late April but Dortmund have repeatedly denied such claims, insisting they are yet to receive an offer for the Germany international.

But the club have admitted they are likely to cash in on the 24-year-old, who turned down their offer of a contract extension earlier in May. Gundogan's current deal expires next summer.

"We have already finished talking with the player and as he did not want to extend his relationship with us, we have thought that he could leave this summer, although it will depend on the offers that reach the club," sporting director Michael Zorc recently said. "At the moment, none have arrived."

Hummels meanwhile has been heavily linked with a move to Old Trafford since the summer of 2014.

The Daily Telegraph reported in May that the Germany international is expected to follow Memphis Depay to the club, with the latter joining Louis van Gaal's side this summer after a deal was struck with PSV Eindhoven.