But Boulter had wrongly thought she had beaten Russian Ekaterina Makarova when she reached seven points in the decisive tiebreak a the end of the third set – and performed a series of double fist-pumps on Court 12 before realising her error and returning to win the match.
The world No.97 eventually triumphed 6-0 4-6 7-6 (10-6) against the world No.60 who reached the semi-finals here in 2015.
And the Leicester City fan admitted: “I thought I had won it at seven points. I was in the moment and I kinda forgot it was first to 10 but I am happy I could dig deep and get through it in the end.
“It was very tough to turn it around because you had just released and you thought you had won the match and you had to get back to work and find a way. I thought I did that really well and I am proud of myself for digging deep.
“I have got to take it light-heartedly. I ended up getting the win. I probably would have been really devastated if I had not. A couple of people have already mentioned it to me. I can laugh it off now. At least I know the rule so it definitely won’t happen again.”
The new rules see a 10-point or champion’s tiebreak played at 6-6 in the final set here. Wimbledon will this year play a tiebreak at 12-12 in the final set.
Boulter faces another rising star – world No.11 and Shenzhen Open champion Aryna Sabalenka – in her next match. But she is also keen to meet the big names also attached to her agency Kin Partners.
“Of course I would like to meet Beckham and Neymar – they are professional sportspeople and I can learn a lot from anyone and I have a lot of respect for them and what they do,” she said.
“But at the end of the day I am just focusing on myself. I am very lucky to have a great support team and that is all I can do at the moment. Whatever else happens, happens.”