Even in the annals of the tennis rankings, there has rarely been anything quite like the scene currently unfolding at the top of the men's game. Five players, all Grand Slam champions, are all in the running for the No. 1 position.

While Andy Murray and Novak Djokovic began the year No. 1 and No. 2, respectively, it is Roger Federer and Rafael Nadal who have dominated the season, returning to the upper reaches of the rankings. In between there's Stan Wawrinka, who has inserted himself into the Big Four era in increasing measure but has not reached the top spot.

Here's a look at where they'll stand when their 2016 grass-court points fall off the rankings, and what they can add in the next few weeks:

Rankings Points (Grass Points Off) Potential Grass Points (Schedule) To Be No. 1 (Following Wimbledon) Murray 7,390 2,500 (Queen's, Wimbledon) Stay level with Nadal; get to the final (plus Queen's 2R) if Wawrinka wins Wimbledon Nadal 7,285 2,000 (Wimbledon) Win Wimbledon, or get in front of Murray and stay in front of Wawrinka and Djokovic.] Wawrinka 6,130 2,500 (Queen's, Wimbledon) Win Wimbledon, with Murray not reaching either the final or Queen's 2R Djokovic 5,714 2,000-2,250 (Eastbourne TBD, Wimbledon) Win Wimbledon, and have others not go deep Federer 4,045 2,500 (Stuttgart 2R, Halle, Wimbledon) Cannot get higher than No. 3 at Wimbledon

WIMBLEDON POINTS PER ROUND:

1R 2R 3R 4R QF SF F W 10 45 90 180 360 720 1,200 2,000

QUEEN'S, HALLE POINTS PER ROUND:

1R 2R QF SF F W 0 45 90 180 300 500

All the top four are within 2,000 points of each other, meaning that any of them could potentially be No. 1 following Wimbledon. That's a big difference from a year ago, when then-No. 1 Djokovic had almost double the points of No. 2 Murray.

Murray and Nadal are almost tied, but Wawrinka and Djokovic are more than 1,000 points back and need to do a lot better than their rivals. While Federer is further back and cannot be No. 1 following Wimbledon, a big grass-court haul would still leave him in a nice position—unlike the others, he has no points to defend for the rest of the season.

Even if the top spot does not change hands at the All England Club, winning the tournament would give any of the five the inside track on the No. 1 ranking. The champion gets 2,000 points, along with a huge helping of confidence. But the competition for No. 1 could still stay heated because they all have some room to add points during the hard-court season.

ANDY MURRAY

Murray went undefeated on grass in 2016, so it's notable that he's still leading the tour even when those are points off. A repeat would see him lock up No. 1, likely for many more weeks. Even if he doesn't win Queen's or Wimbledon, he's still in a good position to stay No. 1 as long as he has a good showing and neither Nadal nor Wawrinka goes undefeated on grass.

Murray also has around 1,000 points to defend during the hard-court season—less than he usually collects, which means he could still add to his total.

RAFAEL NADAL

If Nadal wins Wimbledon, it's quite simple—he’s No. 1. If he doesn't, it isn’t—he has to get to at least the second week, go a round further than Murray and stay within a round of Wawrinka. And if either Murray or Wawrinka have a good run during Queen's, or Djokovic wins Wimbledon, it would take a little more.

But since Nadal wasn't even playing a year ago because of injury, and doesn't have a lot to defend on hard courts, he should keep gaining ground.

STAN WAWRINKA

Getting to No. 1 would be bigger for Wawrinka than the other four, simply because he hasn't been there before. But to do it on grass he would need to win Wimbledon, and that's something else he hasn't done before.

On top of that, Wawrinka would also need some help from his rivals. Specifically, Murray would have to get less than 740 points on grass, minus any increase in the points difference between them at Queen's. If Murray reached the quarterfinal of Queen's and the final of Wimbledon, Wawrinka would not get to No. 1 even if he won both events.

Unless Wawrinka wins Queen's, he'll also need Nadal to not reach the final of Wimbledon.

That's a big task on his least favorite surface.

NOVAK DJOKOVIC

Djokovic is so far back that his position depends largely on the warm-up events—if Murray wins Queen's and Djokovic doesn't win Eastbourne—it’s unclear if he’ll play—the Serb can't get to No. 1 at Wimbledon. Even if he's still in the running when the tournament begins, he would need to win the title, have Murray and Nadal not do very much, and have Wawrinka not have a big grass-court run of his own. That's a lot to pull off.

But with the season he's been having, Djokovic is likely less concerned with the No. 1 ranking and more with collecting wins to build up his confidence. Nevertheless, he'll still want to add points to stop himself from falling even further in the rankings, especially because he also has a fair amount to defend during the hard-court season.

ROGER FEDERER

Federer can't get to No. 1 at Wimbledon, but he can get into contention for No. 1 at Wimbledon. Having played just five events this season, Federer doesn't have a huge points total, and even dropped back a little with his opening-round defeat in Stuttgart. But he has a couple more events on his most effective surface, and that could get him into the same ranking-points neighborhood as the top four at Wimbledon. From there, the seven-time champion would be in a good position to keep moving up.