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Kim Kardashian only lasted three weeks when she competed on Dancing With the Stars in 2008, which explains why the recently single reality star is so proud of her brother Rob for making it to Season 13's final three.

"We were all so blown away by Rob's performances last night," Kim, 30, told Celebuzz on Tuesday. "His freestyle dance was my favorite of the whole season!"

"Each week he works so hard and is always prepared, but never knew he would get a perfect score! We were all amazed and so happy," she added. "Rob is so excited to have made it this far and I am so proud of him."

According to Kim -- who ended her 72-day marriage to Kris Humphries on October 31 -- her 24-year-old brother has undergone quite a transformation since the show's September 19 premiere.

"Doing this show has really changed Rob," she says. "He's really grown up so much and it's been incredible to watch him each week."

Their sister Khloe, 27, is equally excited about Rob's chances of winning the ABC competition.

"By the time last night's show was over my voice was seriously gone! We just couldn't stop screaming after Rob’s freestyle," she says. "Watching Rob improve week after week has been so special for my entire family. His dedication is truly beautiful. We're all just so proud of him!"

Rob and his partner Cheryl Burke, 27, will learn their fate when the season 13 finale of Dancing With the Stars airs live on ABC Tuesday at 9 p.m. EST.