Stefano Pioli becomes the eighth Coach to have represented both Milan and Inter, following the likes of Leonardo and Giovanni Trapattoni.
Pioli will be appointed after the dismissal of Marco Giampaolo and returns to San Siro after he was sacked by Inter in May 2017.
There have already been seven tacticians to have represented both sides of the Milanese divide.
The first was Jozsef Viola, who was in charge of what was then known as Ambrosiana-Inter in 1928-29 and moved across the city in 1933-34.
Giuseppe Bigogno took Milan to second place and then lasted half a season at Inter in 1958.
Gigi Radice was fired by Milan in 1981-82 and had rather more success at Inter for 1983-84.
Ilario Castagner is a rare exception, as he went straight from Milan in Serie B to Inter the very next season.
Giovanni Trapattoni was during his lengthy career the Coach of Juventus, Milan (in 1973-74) and broke Serie A records at Inter in 1988-89.
Alberto Zaccheroni won the Scudetto for the Rossoneri in 1998-99, then had a brief spell at Inter in 2003-04.
The most recent was Leonardo, who was in charge of the Milan bench in 2009-10, then joined Inter in December 2010 to June 2011, winning the Coppa Italia.
He returned to Milan as a director before leaving this summer.
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