But can they hold on to their position?
The boys highly anticipated single 'Live While We're Young' is currently in pole position on the midweek chart while Rihanna's latest effort 'Diamonds' sits at number 2.
However, according to the Official Charts Company, Rihanna could still claim the top spot, trailing 1D by a mere 250 copies.
How close is that?!
[Related Story: Review: Rihanna- Diamonds]
[Related Story: Review: One Direction- Live While We're Young]
And to think, this chart battle wasn't even meant to have happened in the first place.
The big wigs at Rihanna's record label decided to bring the release of 'Diamonds' forward by a week meaning that she would be in direct competition with the pop juggernaut that is One Direction.
This unexpected move could mean that One Direction will be denied their second UK number one come Sunday.
Despite their success across the globe, One Direction's debut single 'You Don't Know You're Beautiful' remains their only ever UK number one single, with follow ups 'Got to Be You' and 'One Thing' along with album 'Up all Night' failing to reach the top spot.
If Rihanna does manage to topple the boys by Sunday, 'Diamonds' will be the Bajan star's 6th UK number one.
Come on Ri-Ri, six is just greedy.