Michael was performing at London's O2 Arena as part of his 'MB World Tour' and 1D star Niall headed along to watch him take to the stage.
After the show, Michael and Niall caught up with each other outside the Arena and posed for a picture together - before the Canadian crooner admitted to having a crush on the Irish boy band star!
Posting the snap on Instagram, Michael told his followers: "Meant so much to have my buddy @niallhoran come and support me at the O2 last night! Love Ya buddy!!! #morethanafriend #mancrush #directioner4life #MBworldtour."
Michael and Niall have been friends for several years now, after meeting on The X Factor before One Direction really hit the big time.
The pair catch up when they can - and are fond of a spot of banter between each other too!
In 2013, after Michael and his wife Luisana Lopilato announced they were expecting their first child together, the jazz singer caused a right old stir on Twitter.
Hacking into Luisana's account, Michael wrote: "@NiallOfficial I wish that you could have been the father!! Hahah I went the 'wrong direction' @michaelbuble says you can be the stepdad."
In a later interview, Michael admitted: "That was me who wrote that! I've never tweeted before as my management won't let me, and my wife said, 'You write something, you always have the good ideas'."
Watch Michael's most recent X Factor performance here: