Rob and Kim Kardashian
FilmMagic; Albert Michael/Startraks
11/22/2011 at 04:00 PM EST
is basking in sisterly pride after watching little brother Rob Kardashian shine
in the finals of Dancing with the Stars
"Doing this show has really changed Rob," Kim, 31, a former Dancing
contestant, tells Celebuzz
. "He’s really grown up so much and it’s been incredible to watch him each week.”
As a tuxedo-clad Kim joined
sister Khloé and mom Kris Jenner in the ballroom on Monday, Rob, 24, scored his first perfect 30 for a daring freestyle dance in which he lifted and twirled pro partner Cheryl Burke
“We were all so blown away by Rob’s performances last night," says Kim. "Each week he works so hard and is always prepared, but [we] never knew he would get a perfect score!! We were all amazed and so happy! Rob is so excited to have made it this far and I am so proud of him."
Rob became an unlikely frontrunner, pulling ahead of favorites J.R. Martinez and Ricki Lake in the race for the mirror-ball trophy, which will be handed out on Tuesday's show.