Beyonce Knowles is back on top of the US charts and this time she's IRREPLACEABLE. The singer's Irreplaceable hit has toppled Akon's I WANNA LOVE YOU on the new Billboard Hot 100. It's her fourth number one as a solo artist. The hit track also claims the top spot on the Pop 100 and Hot Digital Songs charts and makes it to three weeks atop the Hot R+B/Hip-Hop Songs list. It has also been America's greatest airplay gainer for the past five successive weeks. Fergie's back on the rise - her FERGALICIOUS anthem shot up from 10 to number four on the new chart after slipping up in recent weeks. Meanwhile, Canadian rocker Avril Lavigne marks her comeback with the week's highest new entry - KEEP HOLDING ON debuts at 22.