By Alan Smith Liverpool might have to fork out a world-record fee for a manager if Xabi Alonso is to replace Jurgen Klopp this summer. With the former midfielder under contract at Bayer Leverkusen until the summer of 2026, the Bundesliga leaders are demanding a fee of more than £20m to let him go. And it could end up costing more than the €25m Bayern Munich paid to bring in Julian Nagelsmann from RB Leipzig in 2021. Transfer fees for managers remain a relatively new concept – but they are going to become more popular and the amounts will rise further. Here are the top 10 fees biggest paid up u…