While cautious to say that Messi and Ronaldo are icons of their respective teams, Ancelotti admitted that it would be 'great' to have Messi join Ronaldo at the Bernabeu.
Messi's future at Barcelona has been thrown into doubt this season, and the Argentine international did little to dampen speculation at the Ballon d'Or this week when he said that he doesn't know where he'll be playing his football next season.
So, when one journalist put it to Ancelotti the former-Chelsea said it could be possible.
To have both [Messi & Ronaldo] in the same team would be a great thing for us - Carlo Ancelotti
"I believe so yes," Ancelotti said as reported by ESPN. "Although you must bear in mind that Cristiano is the emblem of Real Madrid and Messi of Barcelona.
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"Each one has their own team and their own history, but to have both in the same team would be a great thing for us. It is, however, difficult to think it is going to change."
A transfer from Barcelona to Real Madrid would be problematic but it's not unprecedented - Luis Figo and even current Barcelona manager Luis Enrique have made the switch between the La Liga giants in the modern era.
Real Madrid could feasibly afford to sign the £200m superstar - they're one of the few clubs that have the revenues - but they already boast a Galatico line-up with Ronaldo, Gareth Bale and Karim Benzema in attack.
There was a mini-controversy earlier this month when Bale didn't pass the ball to Ronaldo - and the Portuguese star didn't look happy.
Bale and Ronaldo relationship
But Ancelotti quickly nipped that in the bud, describing the relationship as 'perfect'.
""It seemed to me that it was difficult to pass the ball," Ancelotti said. "It was not necessary to talk about this with Gareth, who is playing very well. He is in top physical condition at the moment. Tomorrow he will play a great game. The relationship between both is perfect."