Gwen Stefani may have thought she knows herself all too well, but a hardcore fan proves she knows the singer better than the personality does in Who Knows Gwen Stefani? segment.

The Grammy Award-winning singer-songwriter battled it out with a superfan during a segment of the Jimmy Kimmel Live show, wherein guests must go head-to-head with other people in answering questions about them. Gaiane, a social worker from Los Angeles, is a fan of the No Doubt vocalist since she was 15.

Stefani admitted she wasn't confident at all about the contest, saying she was Dory. The Finding Nemo character is a forgetful blue tang fish, suffering from short-term memory loss. So basically the "Hollaback Girl" singer casually forgets stuff about her.

The fan also revealed she had been to over 100 concerts and shows of Stefani, so she might just be one of her biggest fans, and added her idol has been a huge inspiration and influence on her being herself. Up for grabs in the competition for Gaiane is a bag, sunglasses, and a dress from the singer's closet, while the 48-year-old fashion designer can win the fan's No Doubt car plate.

The game started to side with Stefani as she answered two rounds of questions rightly. The first query was about the age of the singer's aunt who recently celebrated her birthday. "The Sweet Escape" singer answered "90" correctly, and Gaiane admitted she thought it was 92.

The contest along the way revealed some trivia about Stefani, including the first album she bought, which was a John Cassidy, something the singer got right. However, Gaiane proved she knows the singer better when she consecutively answered the next questions after the first two right.

Kimmel asked during the third round the first song Stefani wrote, to which the superfan answered "Different People." The performer then said that it was a track that ended up on former U. S. President Barack Obama's playlist. Gaiane also answered correctly when asked which character her idol portrayed in the 2004 film The Aviator.

The company that Stefani's dad worked for when she was young was also asked, and the die-hard fan got the answer. The singer revealed that it got her the opportunity to be able to meet Sting, and a throwback picture shows her teen self getting an autograph from the English musician.

Stefani seemed to have redeemed herself when she got the next question right, asking her the camp's name she went to in her seventh grade. However, the last round went to Gaiane, who answered that her idol got featured in Prince's song "So Far, So Pleased," becoming the ultimate champion. That said, she earned the prizes, bragging rights, and title as the person who knows the singer better than the singer herself.