Twitter user @_OwenLFC messaged the club's Twitter administration asking how many retweets he would need in order to receive the prize. He promptly received a reply: 25,000.
Alaba, who is currently on international duty with Austria, became aware of the fan's endeavour and offered his support by retweeting the post to his 1.22 million followers.
With thanks to David, two days later, Owen had reached his target.
Bayern's official account was even kind enough to assure Owen that the signed shirt was indeed on its way.
Bayern's reply. Don't forget Alaba is with Austria 🇦🇹 at the moment. pic.twitter.com/p31iOcA0MH— Owen. (@_OwenLFC) June 2, 2017
The campaign follows on from the success of the #NuggsForCarter hashtag coined by Nevada teenager Carter Wilkerson, who asked a fast-food restaurant how many retweets he would need in order to receive a year of free chicken nuggets. His target is 18 million, and while he is still some way off that target, Wilkerson's tweet went viral and is now the most retweeted post of all time (over 3.6 million).
Watch: Alaba's Ace in the hole and nine other A-udacious efforts