Since Thomas Tuchel was appointed by Chelsea in January, he has faced Jose Mourinho, Diego Simeone, Jürgen Klopp, Carlo Ancelotti, Pep Guardiola and Zinedine Zidane. These truly are the great and good of football management, and Tuchel has beaten them all. Not only that. Tuchel’s Chelsea have also kept a clean sheet against each of these illustrious opponents, shutting down some of the most feared forward players on the continent. Against Real Madrid in Wednesday’s Champions League semi-final, his Chelsea side hardly allowed the Spanish champions a glance at goal, let alone a genuine chance. The defensive strength of Tuchel’s team is bordering on preposterous, with this 2-0 win over Real representing their 18th clean sheet in 24 matches. By contrast, they kept just 26 clean sheets in 84 matches under Frank Lampard. They are a different team now, playing a different game. Chelsea’s solidity is built on the power of the collective: the hard-running of the energetic forwards, the intelligence of the midfielders, the composure of their three central defenders. But a fundamental truth of their season is that, surely, none of this would have been possible without the £22 million purchase of Edouard Mendy in September.