Reese Witherspoon, 46, appeared in just two episodes of Friends in 2000. However, the moments spent with her on-screen sister Jennifer Aniston, 53, were so memorable the actress can still recite their conversations to this day.

Although they have worked together since, Jennifer and Reese first met in 2000 when the then 23-year-old landed the role of Jill Green, the younger sister of Jennifer's iconic character Rachel.

Reese had risen to fame as a film actress, starting in 1991 but became a household name in 1999 with her roles in Cruel Intentions, Best Laid Plans and Election.

Walking on to the Friends set the next year, the budding starlet was intimidated by the star power on set, particularly by Matt LeBlanc.

She recalled, speaking on Late Night with Seth Meyers: "I was terrified.

Reese also shared that she keeps track of how long ago she made her cameo, as she had just given birth to her daughter Ava before arriving on the show.

She added: "That's how I know it was 23 years ago, because now my baby is 23."

Reese's character, although a very small part of the show, is still memorable for the actress as she also recalled one particular line that she cannot forget involving Jennifer and David Schwimmer's characters.

She said: "The funny storyline was I started dating Ross because she and Ross were on a break.