The Italian has explained that he had to improvise in order to get his point across to the former England captain during their time together at San Siro
The now-retired former England captain had two spells on loan at the Rossoneri from LA Galaxy, in 2009 and 2010.
Ancelotti was still at San Siro for the first of those stints and he explained that Beckham's command of the Italian language was not ideal, meaning it was difficult for him to get across exactly what he wanted from the midfielder while trying to play a practical joke on Mathieu Flamini one day.
"First, you tell the Italians, in Italian," the current Real Madrid coach revealed in the Financial Times. "Then, you tell the Brazilians, in pseudo-Italian, and then you tell Beckham, with grunts and gestures."
Ancelotti also admitted that he was put under pressure by Milan owner Silvio Berlusconi to not only rack up trophies at San Siro but also do so with an incredibly attacking line-up.
"The tradition at Milan is to play a good style of football – differently from Juventus, where the most important thing is to win," the former Bianconeri boss explains. "When Berlusconi bought Milan, it was this.
"This was the only reason to play [Andrea] Pirlo, [Clarence] Seedorf, Rui Costa, Kaka, [Andriy] Shevchenko at the same time."
Meanwhile, Ancelotti confessed that he found it difficult to turn Paris Saint-Germain into a title-winning team.
"We had the South Americans, the French, the Italians - the relationship is not easy," he explained.
"The South Americans like to play with each other. The Italians the same. We took six months to get results.
"The players were not used to having a winning mentality. Training was at 11:00 usually. The players were used to coming at 10:30, training – and at 12.30, 13:00, to leave the training ground.
"To change this was not easy; to tell them: 'You have to stay after training, to eat properly, to drink properly, to rest. You cannot miss one day.'
"So, it was important to have [Zlatan] Ibrahimovic, the best player with good professionalism. He was a model for others to follow in training sessions, because he concentrated every time."