After three hours and 45 minutes, both Matteo Berrettini and Jannik Sinner cut exhausted figures on Centre Court. The all-Italian clash hyped in the build-up had turned out to be a late-night classic, with the world No1 only just swiping the contest in four sets against the tireless grass-court specialist. 

But as disappointed as Berrettini must have been to have to come close to taking the narrowly fought tie to five sets, even a shock victory, he took the time at the net to share a hug with his friend and Davis Cup team-mate, even tenderly patting his cheek in congratulations. 

No such scenes are expected in a second box-office tie between two compatriots on No1 Court on Thursday afternoon. Instead, the all-British affair between Katie Boulter and Harriet Dart is likely to have the tension of a simmering civil war. 

Both 27 years old, Boulter and Dart have spent over two decades in one another's orbit, both growing up so emmeshed in the tennis world that their mothers - Sue Boulter and Susie Dart - had even met as players during their own early careers. 

The pair are friends - and Boulter has spoken about how 'awful' it can be to play her Billie Jean King Cup team-mate because that - but as Boulter's star has risen to take in back-to-back Nottingham title wins and a seeded berth at Wimbledon, Dart has struggled to see the same success, making it to her first WTA-level semi-final just this year at the Translyvania Open. The conditions are primed for rivalry laced with needle.

In their senior outings, the pair have met one another seven times, but their's has been a one-sided conflict, with Boulter, the current British No1, besting Dart all but one of the times they've face one another. 

The world No100 will take no comfort that her one victory came not on grass, but on a hard court, nor that grass court have been a vivid green backdrop to two of their frostiest meetings. 

The first came last year, at the Nottingham Open, on the heels of Boulter's 6-3 7-5 victory against her fellow Briton. Boulter was in fact en route to her maiden grass court title, and celebrated the quarter-final win expansively - much to Dart's disapproval. 

Dart took issue with Boulter jabbing a finger at her temple in the direction of her player box, and told her so when they met at the net for a cursory handshake. 

Boulter denied that it had something to do with Dart, and Dart called her out for being 'unprofessional' as the players turned to the umpire, forcing another denial from the winner - who said that she made the gesture 'after every match' and that it was 'nothing personal'.

But Dart struggles to keep her emotions close to her chest when playing fellow Brits, and Boulter in particular, their most recent meeting bubbling up as the player once again found herself unable to keep her cool. 

Back at Nottingham - just weeks before their meeting on No1 Court on Thursday - this time Dart boiled over when the chair umpire deemed Boulter's winner as falling in, rather than out, as Dart saw it. 

'No way!' Dart shouted across court. 'The ball was so far out.'

When the chair umpire confirmed her call, Dart repeatedly protested before saying that it was 'embarrassing' and that she was 'embarrassing herself' before receiving a reprimand. 

During the change of ends, Dart's fury showed no signs of subsiding. 

'I promise you,' she continued, 'if you watch it back, I will bet £50,000 that ball was out. Honestly. I would shake your hand right now. 

'It's a joke how far that ball was out.' 

Boulter sensibly stayed far away from the conflict and knuckled down to see out the 6-7 (5-7) 6-4 7-5 match, which lasted well over three hours. 

At this point, the British No1 stressed after her first-round victory against Tatjana Maria, the pair 'know each other's games inside-out, back-to-front', and Boulter is gearing up for a challenging clash as a result. 

'Playing a Brit in the UK on the grass is never an easy draw and I’m expecting an absolute battle,' Boulter said on Monday.  

'I do have to draw on the last things that I have played with her and use that to my advantage in the next round. I think it's going to be extremely tough. I have a lot of respect for her on this surface. It's one of her favorite ones.

'This is actually her home club. She's been here since she was a tiny tot with her mum.'

But Boulter stressed that she was 'excited' by the challenge, adding: 'you have two Brits here who are playing some very good tennis. She's someone that's going to make it very hard for me. I'm going to have to bring my A-game.'

Dart - then unaware whether she would be facing Maria or Boulter after her early dismissal of Zhuoxuan Bai - was less easy to read on how she felt about another meeting with a rival that has become one of her toughest opponents to beat. 

'I have nothing to lose, that's for sure,' Dart pondered. 'For me, a big goal was just trying to get through round one. Last year was I would say heartbreaking for me, but also put me in a place where I had to dig deep towards the end of the year.

'I always think things happen for a reason. They definitely did. This year, I'm very much focusing much more on the process, how if I can play some good tennis, I can give myself the best opportunity to play well, to put myself in a position to win matches. That's kind of all I can do.'