The Backstreet Boys also plugged the new song on social media: "What a GLORIOUS day it is ... we've been asked about the possibility of a collab like this for the past 20 years and today is the day!! #BritneyXBackstreet is finally here!"
Matches is an electro-pop track produced by Mike Wise and Ian Kirkpatrick.
This is the second single released by Spears in a couple of weeks, following Swimming in the Stars last week.
Both tracks are part of Spears' re-released version of her 2016 album Glory.
The musicians released their joint single on the same day Taylor Swift announced and released her second album, Evermore.
