As they remain at the top of the women's game the Williams sisters, Serena and Venus, once again took tennis from the court and placed it in the centre of a debate on age as well as sibling affections and rivalry.

Serena, her whorls of hair sprouting up and out over the sides of her head, was very much the Amazonian warrior; Venus, with hers tightly gathered in a bun with a white visor, resembled some buttoned-up country club heiress.

Both cut different figures in a strangely emotionless match where neither sister wished to exploit the others discomfort at losing a point. As it fell, Venus, the elder of the two, lost the points, the games and the sets in a 6-4, 6-3 defeat.

The ‘Serena Slam’ remains intact with both players accepting that sport is about competition and subjugation of the opponent, even if it is completely at odds with the affection they share for each other.

Neither has ever been able to fully explain their conflict of possessing sisterly love and affection, part of which is willing sacrifice, with the need to exploit each other’s weaknesses on court.

Serena triumphed, as she has done in 14 of their 25 meetings, with the crowd instinctively falling behind the older woman, sensing perhaps that she was the more vulnerable, a carrier of more baggage.

It was also within the grasp of Venus to halt the progress of her little sister’s assault on the four grand slams in this calendar year, as well as Steffi Graf’s heap of 22 grand slam titles.

A win at Wimbledon would take Serena to 21 and another at the US Open would pull her level with the great German player.

Greatest player

“When we’re off the court, she’s Serena, my sister. When we’re on the court, she’s Serena, my opponent,” said Venus, who also suggested that her sister has more years to play.

“I don’t think she’s done, so we’ll see what more she does. I don’t think she would call herself the greatest player of all time because she respects everyone else and the accomplishments they’ve made.

“But the level she’s playing at is unprecedented. I can say that with confidence. So make what you will of it. Then when it’s a wrap, it will be easier to make labels and not offend anybody.”

The Centre Court boomed when both got up and running, Serena taking the first two games and then handing them back for 2-2. But when Serena broke serve for 3-2, she closed the door on the set and there was no way back for Venus.

The Serena serve was hard and consistent, her ground strokes controlled and the unforced errors low. Venus met each with equal ferocity but with Serena’s six aces, or a free point in every game she won in the first set, it was the number one player who set the challenge and asked Venus to meet it.

Singing off the strings

Venus’s third double fault of the match in the second set was unfortunate as it lamely handed her sister a service break for 4-3. With the ball singing off the strings, Serena ruthlessly took advantage.

While the rallies were athletic and aggressive, there was little venom or spite in the match. Venus made one Hawkeye challenge but the character of the match was civil and constrained and refused to develop into anything openly combative or edgy.

Serena finally took the match on her serving game. With three match points available, a long return from Venus brought it to a silent close. What did you say to each other at the net afterwards, Venus was asked. “Sisterly things,” she replied mysteriously.

Serena, younger and a little more spirited, was less guarded than her 35-year-old sibling. She has been able to tuck the sister thing away, although it has taken her some time to just see an opponent across the net.

“You know, in the beginning, I had to really kind of focus on that. I had to really think like, ‘No, I’m not playing Venus’,” said Serena. “But now, you know, I wasn’t thinking like that at all.

Tough opponent

“I’m thinking, I’m playing a tough opponent. She’s been playing so well. Oh my God, how am I going to be able to overcome this? It wasn’t necessarily playing Venus, it was playing my opponent and the ball.”

Serena meets Victoria Azerenka in the quarter-final. Azerenka beat 'Little Hingis' Belinda Bencic 6-2, 6-2, while Maria Sharapova advanced in two sets. The Russian, winner here in 2004, defeated the unseeded Kazak player Zarina Diyas 6-4, 6-4.

It was a successful day for American players with big serving Coco Vandeweghe taking out the sixth seed Lucie Safarova. She now meets Sharapova.

Teenager Madison Keys, coached by former Wimbledon champion Lindsay Davenport, faces the experienced Agnieszka Radwanska. She stopped Jelena Jankovic in her tracks, while Caroline Wozniacki goes home, beaten 6-4, 6-4 by Spain's Garbine Muguruza.