It's a semifinal that is too close to call: Andy Murray, the home hero, versus the universally popular Roger Federer, and even the Centre Court crowd likely will be split over whom to support.
Federer, whose most recent Grand Slam title came in 2012, when he beat Murray at the All England Club, hopes to win Friday and go on to score an eighth Wimbledon title, and an 18th Grand Slam, on Sunday. Murray, revitalised after turning to Amelie Maursemo as a coach and recovering from a back operation, is looking to win his first Grand Slam in two years.
The stats highlight how close the pair has become, with the Swiss leading head-to-head 12-11, so we got three men with unique insights to try to separate the pair.
Federer's idol, Rod Laver, the only man to achieve the calendar Grand Slam twice; Murray's former coach Mark Petchey; and John Lloyd, a former Grand Slam finalist who captained the Scot on Britain's Davis Cup team, answer seven key questions:
Does grass give Federer his best chance of winning an 18th major?
Laver: Yes, I would think so -- I see Wimbledon as his best chance. The speed and the height of the bounce works for him. Roger likes the ball around hip-high or lower. If it goes any higher, you get errors.
Trying to put more spin on a ball that's up high, that's not easy to do. He wants to win a Grand Slam. Certainly, he loves the game and would probably play anyway, but he's been training to be in his best shape with his game and on the physical side. All the time he is thinking: "I want to win this."
Will Federer's World Tour Finals mauling of Murray affect things?
Petchey: That match was an aberration and Andy is strong enough mentally to think that that match didn't happen. Obviously, from Roger's perspective, that match did happen, but it didn't for Andy. He is a different player now.
He had played a lot of tennis at the back end of last year, he was fatigued, and there were a few other things going on, such as changes to the team. It's very easy for Andy to stick that match in the trash and hit permanent delete.
Can Murray cope with a divided Centre Court crowd?
Lloyd: The crowd won't be anything like as pro-Andy as they usually are. Facing Federer, that's the closest that Andy comes to playing a neutral match in Britain, with the crowd not heavily in his favour. Andy understands that and I would imagine he won't be upset by that. He realises that Federer is unbelievably popular, even with Brits.
Andy also appreciates that, even though we're in Britain, a lot of foreigners buy tickets. A lot will depend on how the match goes. If Andy has a good start, even more support will swing to Federer as the crowd will want to see a close match. That's something he has to be ready for.
What gives Federer his best chance of victory?
Laver: This is the best Roger has served in years, and he will want to keep that up. Maybe he has been throwing up the ball a little bit more, and going for it more. He's getting a lot of free points, and that builds your confidence. He can rely on winning his serve. Roger will use his backhand slice, maybe dropping it short and getting Murray to come to net when he doesn't want to. When he gives a short, low ball, Andy can't be that aggressive. And Roger is in position to hit forehand or backhand passing shots.
Lloyd: This is the best surface for Federer -- it gives him the best chance of beating Murray. The surface was made for him. But his game will have to be firing. Roger has a lot of respect for the way Andy plays, [but] that respect came gradually. He now appreciates what Andy has and that he is tough to beat. But on this surface, he will fancy his chances.
What gives Murray his best chance of victory?
Lloyd: Andy has to be aggressive. He can't just think about counterpunching. He has to take Roger on, but be careful on his own second serves. He can't start pushing his second serve, as then Federer will get on to it.
Federer will come in quite a lot, and Andy doesn't mind that. But Andy wants Federer to come in on shots he doesn't want to come in on. That means hitting the ball deep. If Andy keeps on dropping the ball short, which would invite Federer to attack him, he's going to be in trouble.
Where will the match be won and lost?
Petchey: This is too tight to call. Roger has been playing some awesome tennis so far in the tournament, but now he's going to have a different caliber of opponent in Andy. The talent gap isn't big, and it's going to be about who executes best.
It's about playing your tennis on the big points. Most of the time when they play it's going to be tight, and when you get a chance, you need to find something special, and they're both capable of doing that. That's what it's going to come down to.
How important is the Federer-Murray rivalry?
Petchey: Roger's rivalry with Andy is probably the third-most important [for the Swiss]. I would put it behind his rivalries with Rafael Nadal and Novak Djokovic, in terms of quantity and also at times in terms of quality. But with Roger getting towards the back end of his career, these are special moments for him. And these are the moments that he doesn't want to let go. For Andy to play against one of the greatest players of all time, that's something he will relish.