I just searched. Justin Timberlake's "Summer Love" was #1 while "Umbrella" was #2. It had a low bullet, so it looked like she was about to pass him, but then "Big Girls Don't Cry" crept up on her, then her bullet (Rihanna) suddenly dropped, causing Sean Kingston's "Beautiful Girl" to trample her.
So an unofficial single stopped her from #1.
And I also saw some of Tierra's post, I can't believe how quickly your opinions change. You were hating on "Gimme More" hard...