Mats Hummels
Hummels named new Dortmund captain.Getty

Borussia Dortmund have named Mats Hummels their new club captain in a move that could change Manchester United's transfer plans again.

United and Louis van Gaal were handed a setback in attempts to strengthen their defence this weekend when Thomas Vermaelen sealed his move from Arsenal to Barcelona, signing a five year contract at the Nou Camp.

The United boss had been keen to add the left-footed centre half to his backline as he continues to fine tune his 3-5-2 formation ahead of the new season but those hopes were dashed by Arsene Wenger, who was not willing to see the player join a domestic rival.

World Cup winner Hummels has been another name frequently linked with the club despite Dortmund's persistent claims the player will not be sold and weekend reports have suggested a fresh bid of £25m could be made.

But following Sebastian Khel's decision to step down as skipper ahead of the final of his 14 seasons at the Westfalenstadion, Jurgen Klopp has handed Hummels the armband in a move that all but confirms the defender's continued presence at the club for the 2014/15 season.

Earlier in the summer the 25-year-old admitted that one day the idea of moving to Old Trafford may appeal to him, but insisted it was of no interest to him at this moment. "I never think about that or talk about it because it is something that isn't important for me right now," Hummels was quoted as saying by the Daily Telegraph in June.

"Maybe it will be some day, but I don't expect it to be like that this summer."

Dortmund have also named Marco Reus, another to be linked with a move to Old Trafford, their vice-captain ahead of the new season.

During United's impressive preseason tour of the United States, van Gaal used Jonny Evans, Phil Jones, Chris Smalling, Michael Keane and Tyler Blackett at centre half and while he is pleased with how they have adapted to his adjustments, he believes the club may need further reinforcements following the departures of Rio Ferdinand and Nemanja Vidic.

"I am looking at the defenders we have first," van Gaal said last month.

"And, when you see our three matches, we are doing well, I think. But it is right that we are looking for defenders, because a lot of defenders have gone.

"We have to replace them but I also like Michael Keane and Tyler Blackett."