Atletico chairman Enrique Cerezo confirmed the presence of the Italian at the Vicente Calderon after the match, which Atleti won 2-1 with an injury-time own-goal from Weligton under pressure from the Colombia star.
"We know that Mancini has come to watch the game but we are calm with the topic of Falcao," Cerezo said before joking: "I suppose Mancini is here to look for a house in Malaga!"
Cerezo has previously had to fight off interest from Chelsea in Falcao, who has scored eight goals already this season - and a hat-trick against the Blues in the European Super Cup.
He is under contract until 2016 but said at the weekend: "England? One day, I could go. It is a game I have watched for a long time and one day I would like to sample it.
"I used to watch it on television when I was a kid. Players like Roy Keane, Eric Cantona, [Gianfranco] Zola. But the one I supported was [Faustino] Asprilla, when he was at Newcastle.
"I think I could adapt to England. I think I could score goals."
Falcao joined the Rojiblancos from Porto for more than £30m in 2011 and scored 36 goals last season as they won the Europa League.
He also won the Europa League and Portuguese Superliga the previous season with Porto.