Lampard becomes the 14th managerial appointment under Roman Abramovich's 16-year reign in West London, and the first Englishman to take the top job in that time.

The former England midfielder takes over after his debut managerial season in charge of Championship outfit Derby County, where he guided the team to the play-off final.

In perhaps a football first, Blues fans were forced to wait for the news as the announcement was delayed by Instagram a experiencing technical fault.

In due course, the 41-year-old was named as replacing Italian manager Sarri, who traded London for Turin and the Juventus job after enduring a stop-start campaign in his debut season in English football. 

Amid mounting speculation a deal was imminent after Lampard was given permission by Derby to miss training to discuss terms with Chelsea, the London club confirmed his appointment in an announcement on Thursday.