Poker Face was the biggest

1. Lady Gaga - Poker Face
2. Beyonce - Single Ladies (#1 if you count the video )
3. Katy Perry - Firework
4. Rihanna - We Found Love
5. Miley Cyrus - Wrecking Ball
6. P!nk - Just Give Me a Reason
7. Kelly Clarkson - What Doesn't Kill You (Stronger)
8. Gwen Stefani - Hollaback Girl
9. Avril Lavigne - Girlfriend
10. Taylor Swift - I Knew You Were Trouble

Starting her career =/= releasing her first solo album.

Her career started in the 90s with Destiny's Child, and she embarked on her solo career in 2003.

Queen of Pop's 14M selling, ICONIC smash hit Poker Face, obviously

And only one of those sold 14 million worldwide.

Let's not exaggerate We Found Love's success.. Diamonds was bigger in Europe for example.

Poker Face.