“Blue is the colour, football is the game,” as Chelsea fans like to sing. Tonight their team is playing Barcelona in the semi-final of Europe's Champions League in the Catalan city's Camp Nou stadium. But here's the thing. The guys from London are being coached by an interim manager.

Guus Hiddink, Chelsea's temporary boss, was brought in by Roman Abramovich, the club's Russian owner, in February, after the sudden dismissal of his predecessor. Mr Hiddink, who was already manager of the Russian national team, agreed to look after the Chelsea side until the end of the season in May.

Once he was installed, the team's flagging performances soon picked up. Talented players, who had seemed flat and uninspired under the former manager, began to look like superstars again. After a brilliant victory away at Liverpool this month one sports reporter declared: “The Hiddink effect is looking like something close to alchemy.”