text: The news that Jurgen Klopp will leave Borussia Dortmund in the summer has raised the probability that key members of his squad will depart too. Klopp has painstakingly built a team in his image during his seven-year tenure at the Westfalenstadion and achieved considerable success. Dortmund were Bundesliga champions in 2011 and 2012 before they reached the final of the Champions League in 2013. Jurgen Klopp has announced he is to quit Borussia Dortmund at the end of the season . Klopp has enjoyed seven successful seasons at the Westfalenstadion but has decided to call time . But the signings of Mario Gotze and Robert Lewandowski helped Bayern Munich re-establish their dominance and Klopp's exit is the end of an era. It could signal the break-up of the Dortmund squad and we take a look at four players who could follow Klopp out of the club this summer. MATS HUMMELS . Even before Klopp's shock announcement, it looked highly likely that Hummels would be leaving at the end of the season, most likely to Manchester United. The Germany World Cup-winner is considered one of the best defenders in the game and would add steel to any back line. Klopp revealed recently that Hummels, 26, had been 'thinking things over,' adding that he believed he was good enough for United. Defender Mats Hummels has been linked with a move to Manchester United this summer . ILKAY GUNDOGAN . The 24-year-old midfielder has also been linked with a summer move to the Premier League, with Arsenal, Liverpool and Manchester City among those interested. At his best, Gundogan can take control of a midfield battle and is more than capable of unlocking defences with his range of passing. He hinted in February that he was ready to sign a new contract but then stalled and Klopp's departure could make up his mind for him. Midfielder Ilkay Gundogan has been linked with a number of Premier League sides . CIRO IMMOBILE . The Italian striker only arrived at the Westfalenstadion from Torino last summer but hasn't lived up to expectations as Lewandowski's replacement. A measly return of 10 goals for the season has hardly compensated for the loss of their star striker to Bayern last summer. There have been suggestions that Dortmund will listen to offers for Immobile and he would most likely return home to Italy, perhaps to AC Milan. Ciro Immobile (left) has struggled to compensate for Robert Lewandowski's departure to Bayern Munich . NEVEN SUBOTIC . The Serbian defender had ears burning in the Premier League when he said last week that he won't decide his Dortmund future until after his summer holidays. He also added they he yearns to play in a league that is more physical, saying: 'How can I do my work when my opponent starts crying without contact?' Subotic has been linked with Manchester United and Arsenal, offering a possible alternative if Hummels doesn't want to make the move. Defender Neven Subotic celebrates scoring in the German Cup quarter-final with Hoffenheim .
target: Klopp will leave Borussia Dortmund in the summer after seven years .
  His departure could means the break-up of his talented squad .
  Defender Mats Hummels has been weighing up a move to Man United .
  Midfielder Ilkay Gundogan has been linked with Premier League clubs .
  Ciro Immobile could return to Italy following poor goal return .
  Neven Subotic has hinted his is keen on a  move to England .