Sports’ greatest rivalry has hit a speed bump as Rafael Nadal pulled out of tournaments in Toronto and Cincinnati prior to the US Open due to an injured right wrist.

Even though Rafa’s a southpaw server, wrist injuries to the dominant and non-dominant hand alike are becoming more common as players engage in a power game that puts a lot of stress on the joints. This is particularly true in the case of Rafa, who has such an intense style of play.

This sets up a number of intriguing scenarios for the rest of the season. First, whatever Nole does – and remember he’s about to become a first-time father – he’s assured of remaining the No. 1-ranked player through the summer and probably through the rest of the year, because Rafa will not be able to defend the points he gained winning Toronto’s Rogers Cup and the Western & Southern Open in Mason, outside Cincy last year. (Under the ATP rankings system, if you can’t defend your points, you lose them.)

Secondly, this makes it harder for Rafa to defend his US Open title. He has never defended a Slam except for the French Open on his beloved clay, of course. He is, however, capable of coming back from an injury and playing brilliantly. But he has also taken more time than announced for past injuries, too.

Thirdly, with Andy Murray still on the comeback trail (back injury) and Rafa out for three weeks, there’s a chink in the armor of the Big Four that opens a window for a Dimitrov or a Kyrgios.

Will they take advantage of the situation?

Let’s just say it’s going to be an interesting August.