LONDON -- It was 24 years ago that a phone rang from somewhere in the upper reaches of the University of Chicago Pavilion, postponing John McEnroe's serve to brother Patrick on match point in the finals of the Volvo Tennis tournament.
"Dad, it's Mom calling," John shouted over to his father, John Sr., sitting in a baseline seat behind Patrick.
"Tell her I'll be home soon," Patrick called out without missing a beat.
"She said you should miss this return," John retorted.
It got great laughs among the spectators, who probably had no idea just how necessary the bit of comic relief was for the competitors.
The two hugged at the net after John closed out the 3-6, 6-2, 6-4 victory, and expressed their emotions -- and relief -- soon after.
"I'm glad that's over," Patrick said, sighing.
"Every emotion you can imagine is there, every single one," John said. "You're always trying to win, yet you know it's your brother. You're proud of the way he's playing, and yet you don't want him to beat you. ... I was aging by the minute out there."
With Serena vs. Venus Williams XXVI set for Monday's fourth round at Wimbledon, sibling rivalries again are taking center stage with the Williamses elevating the normal push and pull between brothers and sisters to a level to which few of us can relate.
"If I see her in a match in a tight spot, I know exactly what that feels like," Venus said. "I think that's a unique relationship that is pretty rare in sport, that she and I share. There are other siblings who have this affinity that we share."
And then again, perhaps not.
"I don't think anybody can relate to this," Patrick McEnroe said. "I think we can understand some of the feelings, but there's no way anybody can really say. I mean, imagine you're walking out on Centre Court at Wimbledon on Monday, and there's all these things going around."
The fact that they have played 25 times, McEnroe said, might make it a bit easier. "Maybe they can go out there and just play," he said. "If not easier, maybe it gets more manageable."
But in this setting, with a consecutive Grand Slam streak and potential calendar-year Grand Slam at stake for Serena, combined with the drama of a possible return to glory for Venus in the same place she has won five titles -- including her last Grand Slam singles title in 2008 -- the drama quotient is raised that much more.
If it weren't for Serena, Venus Williams would likely be the best story in women's tennis this year.
"But now she's in the way of this potentially historic year and it happens to be her sister," McEnroe said, shaking his head.
It is that conflict to which the others can relate.
"It's the worst draw," Agnieszka Radwanska responded bluntly when asked about playing a sibling.
The Radwanska sisters have played four times as pros, with older sister Agnieszka, 26, and ranked 13th in the world, holding a 3-1 advantage over sister Urszula, 24, ranked 107th. Agnieszka has won the past three.
"We played a couple times in the first round, but it was a long time ago and so many times in the juniors semifinals, doubles as well, but yes of course, that's the worst thing that can happen," Agnieszka said.
"I can just imagine what [Serena and Venus] feel if they play each other for sure."
Maggie Maleeva, one of three Maleeva sisters who played professional tennis from the '80s through the early 2000s and the only set of three tennis siblings ever ranked in the top 10 at the same time, once called playing against one another "the most difficult thing we had to do."
Of the 15 times they played one another, including five Grand Slams, the older of the two won 14 times, the only exception a default by Manuela against Katerina in the second set of the 1991 Canadian Open semifinal.
In the '92 US Open, after eliminating Martina Navratilova in the second round, Maggie, at 17, defaulted to Manuela in the second set of the quarterfinal (she was trailing -2, 5-3).
"We tried to go on the court and just play, but the fact was there wasn't a rivalry between us," Maggie said. "The way we were educated at home was to always help each other, and it was very sad when one of us lost. It just didn't feel right to be competing."
When Mike and Bob Bryan were playing junior tennis, they have said, their parents would have one of them default if both got to the finals to avoid one becoming arrogant or the other getting too discouraged.
The integrity of the Williams sisters and father/coach Richard has been questioned repeatedly over the course of their 17-year series. Did Richard dictate who would win? Did the sisters themselves have an innate sense of who needed to win more?
At Wimbledon in 2008, after losing to Venus in straight sets, Elena Dementieva said of a possible Venus-Serena matchup: "For sure it's going to be a family decision."
She later pulled back from the comment, saying her poor English was to blame. But the damage was done once again, and Venus called the claim "ridiculous, disrespectful and pretty offensive."
This week the discussion began anew. But there are obviously many other factors in play.
Though Patrick McEnroe was not at the level of his older brother when they met in Chicago in March of '91, Patrick was playing the best tennis of his career but was still ranked 45th (eventually reaching a high of 28th). John, while at the end of his career, was still the former No. 1 and seven-time Grand Slam singles winner.
"This was actually a time when I could have potentially won the match," Patrick said. "And I remember thinking, really thinking, during the match, 'Do I really want to win this match?'
"John always talks about how 'God forbid he should lose to his little brother.' Well, I actually didn't really deep down want to beat my brother. It wasn't something that drove me because, one, he was so much better than me, plus he was a lot older than me (by seven years), so I looked up to him in a lot of ways.
"He was also someone who really supported me in my career when I came out of college, and I wasn't even sure I wanted to be a professional player. So that one match was interesting because it was pretty close, and I remember thinking if I beat him, he wouldn't have talked to me for a year."
Serena said Friday night that Venus, her older sister by 15 months, was playing well and would have the advantage.
The little-sibling feeling, Patrick McEnroe said with a laugh, never goes away.
"Even now when I play with John and we go hit in the indoor courts here, I'm still the younger brother, so there's always that dynamic," he said. "Obviously [the Williams'] dynamic has to be different in some ways because of where they are on their levels, but it's certainly difficult."
From the outside looking in, it's considerably easier.
"I think it's a great thing [that they're playing] each other," said Caroline Wozniacki, a close friend of Serena. "It means that they're doing well ... [and] at the end of the day, I think they're very lucky to have each other on the tour. I wish I had a sister who could play as well on the tour, but I don't.
"I'm sure it's tough, but I think it's great to be able to share that."