She and Seira – who had not partnered before – “just really enjoyed ourselves”, she said.
“I didn’t feel any pressure whatsoever. I’m really happy about that.
“It was amazing to play on Court 7 because we had an amazing crowd there to support us and it just felt really easy to keep playing and just enjoy what I’m doing.”
The achievement by Lucy and Seira, the world number 16, is even more impressive given that their opponents included the top seed, 17-year-old Luna Gryp.
The Belgian had given Lucy a baptism of fire when they played each other in her first match of the singles competition.
“Because I am so young, I don’t want to put too much pressure on myself,” she told the BBC, speaking earlier in the week.
“Luna is a great player, she’s very experienced. It’s my first time taking her to three sets, so I’ve got to take that positive out of that match, and go back to training and fix those errors.”