Williams, at 39, is the oldest woman in the singles while fellow American Gauff, at 15, is the youngest ever to come through the qualifying tournament.
Gauff describes the draw as "a dream" and she might well wake up on Monday morning pinching herself, as this time last week she had no idea she would receive a wildcard into the qualifying tournament and was preoccupied with schoolwork.
After winning her third qualifying match to book her place in the draw, she revealed that her first memory of watching tennis on television was of Serena and Venus Williams who had won 10 Grand Slam titles before she was born.
Now 'Coco' as she is known will play against her idol in front of a packed showcourt crowd in a clash of the generations.
The level-headed teenager was taking it all in her stride though and if there were nerves as she practised at the weekend, she was hiding them well.
"I kind of felt like I was going to play one of them," Gauff said. "Many people have been like 'do you like your draw?' -- I love my draw. Playing one of the greatest players of all time is a dream -- I'm excited to see how I do."
Even 23-time Grand Slam champion Serena, who usually gets too nervous watching sister Venus, is intrigued.
"She's so cool. She's a great girl. I love her dad. They're just really cool people," Williams said on Saturday.
"It's a great moment for her and for Venus. She's playing against a player that actually reminds me of Venus. I think I might, might watch. I always get nervous watching Venus."
Swiss great Roger Federer, whose management company Team 8 also looks after Gauff, is excited.
"I'm super happy for her. I saw the last couple of games when she qualified. Obviously everybody was waiting to see what the draw was going to be like. I think that's fascinating, that she plays Venus now," he said.
"It's a great story. Coco is a nice girl, works really hard. I think she's got a wonderful future ahead of her."
Gauff, who won the French Open junior title aged 14, is coached by her father Corey who once played college basketball for Georgia State. Her mother Candi was a college gymnast.
"I feel blessed because my parents never put limitations on my goals," Gauff said at Roehampton this week. "My parents always told me to shoot as high as I wanted to."
Venus could be excused for feeling her age a little as she walks out to face a player 24 years her junior but Gauff does not regard her as old.
"I don't think of Venus as old -- she's still killing the game right now," she said.
(Reporting by Martyn Herman; editing by Clare Fallon)
