Kaley Cuoco has no shame in the fact that she fell in love with Johnny Galecki at first sight.

Credit: Getty Images

From 2007 to 2019, Cuoco, who is 36, and Galecki, who is 47, played Penny and Leonard Hofstadter on CBS’s hit sitcom The Big Bang Theory.

Credit: Getty Images

Along the way, their chemistry led to a real-life relationship between 2008 and 2010.

Credit: Getty Images

In an excerpt from an upcoming oral history of the show, the two people who used to date talk about how they met. Cuoco said, "I had a very big crush on Johnny early on."

Credit: Getty Images

She said this in an exclusive excerpt from Jessica Radloff’s book The Big Bang Theory: The Definitive Inside Story of the Epic Hit Series that was given to Vanity Fair.

Credit: Getty Images

He looks so cool. At the time, we were both with other people, but I only had eyes for Johnny.

Credit: Getty Images

Then, when I realised he liked me too, I thought, "Oh no, this is going to be bad."

Credit: Getty Images

Still, Galecki didn’t know at first that Cuoco liked him. "I have a healthy ego, but you really have to hit me over the head to let me know you’re flirting with me,

Credit: Getty Images

he said. "Before I went out with Kaley, I had no idea what a crush was." But Cuoco says there was no denying their characters’ "chemistry"

Credit: Getty Images

even before they told each other they liked each other outside of work.

Credit: Getty Images