Blair opens up to ET about how Gellar helped nurse her through some of her darkest days battling multiple sclerosis.
Selma Blair has always had Sarah Michelle Gellar in her corner -- and Dancing With the Stars is no exception! Gellar was in the crowd on Monday night to cheer on her longtime pal, who absolutely stole the show on Elvis night with an impressive cartwheel-split maneuver in her Jive to "Jailhouse Rock."
"It feels too amazing, surreal," Blair tells ET's Matt Cohen backstage after the taping, gushing over the support from Gellar and Amanda Kloots from the audience. "It feels so great to have this perspective in life and Sarah's been with me, honestly, from the start of me moving to Hollywood."
Blair continues, "She rooted for me to get the part in Cruel Intentions, worked with me on it, we became fast friends forever."
The 50-year-old adds that Gellar was among those who helped to nurse her through some of her darkest days of battling multiple sclerosis.
"She was my biggest supporter to get me through and feed me, and do things when I was going through a really, really bad time physically and emotionally," Blair admits. "It's just so amazing. She kind of cried with me, going, 'I really didn't think you'd walk again' ... and you feel like that when you can't, you know?"
Blair has been doing much more than walking during her turn on the dance competition show. Donning black-and- white jailhouse ensembles, the actress was in total control as she and Sasha Farber breathed new life into an iconic Elvis tune this week, showing off Blair's impressive range after her emotional, ethereal number last week. The judges awarded her scores of 8 across the board for a grand total of 32, while Carrie Ann Inaba gushed, "There's no other way of saying it, but you make it look so much easier than it must be for you."
Blair's partner, Farber, tells ET backstage, "The fact that someone said that she [wouldn't] know she would walk again, but yet delivers a dance like that, is just -- for anyone at home, the true inspiration is right here."
Blair says that being able to do a cartwheel again was one of her main goals after undergoing a stem cell transplant in 2019.
"I was like, 'OK, I better be able to do a cartwheel again' 'cause I used to love to tumble when I was really little and I always would stay like that," Blair says, noting that she lost the ability to figure out how to maneuver her body through space in that way. "So to be able to do a cartwheel now and go into the splits again, it's like 'Woah, I actually changed. Something actually corrected in my brain, like I can do that!' And yeah it's just a joyous thing."
Gellar recently told ET that her daughter, Charlotte, was so excited for Blair's Dancing With the Stars debut that she almost missed a major milestone.
"I'm excited," Gellar said at a special screening of her new Netflix teen drama, Do Revenge, earlier this month. "I think my daughter takes the cake as the most excited. She almost gave up her 13th birthday to be able to be there for her first performance. So I said, 'No, you don't give up, that's a once-in-a-lifetime thing. You have your 13th birthday. We'll go later.'"
For more from that interview, watch below.