Few rugby fans are as passionate as this.
Michael Hartnett shared a video of his niece's reaction to Johnny Sexton's performance in last weekend's Six Nations match with Scotland.
Mollie's is seen cheering "Yes Johnny, you did it! Come on Ireland!"
Her uncle says he didn't think his video would be so popular.
"She is a real little trooper and always good for a laugh. She seems to be able to bring a bit of joy to anyone who has seen this."