Among the people to have been left surprised by Alaba’s gesture was Bayern Munich president Herbert Hainer.
Alaba spent 13 years at Bayern Munich and made 431 appearances in total for the club, scoring 33 goals.
The Austria international won ten Bundesliga titles with the Bavarians, two UEFA Champions League trophies, six DFB-Pokals, two FIFA Club World Cups among numerous other honours.
He joined Real Madrid on a five-year contract this summer after his Bayern Munich contract expired.
Boateng, who also joined Olympique Lyon on a free transfer after leaving the German champions recently, has asked for Alaba to be cut some slack.
"Everyone knows what importance Bayern has for David. That he did that was determined by the situation or maybe a photographer asked him to do it. You don't know," Boateng told Sport1.
"One hundred per cent he had no bad intentions in mind. You don't have to make a fuss about it.
"For me, Lyon is now my new club and I will never forget that I was with Bayern for the last 10 years.
"For me it starts all over again, but you don't have to overdo it. I hope that something will develop here for me and that I will be successful with the club. It will be important that I identify with the club."