Both stars are on course to hit one billion views on the video scree...
Gaga is expected to hit the milestone later this month (Oct10), while Bieber is right behind her and should get there by 1 November (10).
And both are way out in front - the next closest artist to them is Michael Jackson with 600 million views.
Bieber might not be the first to get to one billion views but his Baby video is YouTube's most-watched promo.
