The final four in Cincinnati is set, and in an interesting development, no player in the semifinals is among the favorites to win the 2017 US Open. For that reason when one looks at the draw sheet for Cincinnati it's easy to forget that it is a Masters Series event. John Isner, Grigor Dimitrov, David Ferrer, and Nick Kyrgios are the semifinalists this weekend. Kyrgios is the 9th favorite to win the US Open when one consults bet365's betting odds, making him the strongest favorite among the quartet of players just mentioned.

The outright favorites remain Roger Federer and Rafael Nadal, and it's easy to see why from some points of view.

They've combined to win the Grand Slams this season, they have each won the Flushing Meadows title multiple times before, and they will each be seeded highly in New York. However, there's plenty of room for criticism for each player with perhaps the most obvious criticism against Nadal.

Nadal hasn't impressed since Roland Garros

The Spaniard has lost his tennis touch a little since winning the French Open. He may be the No. 1 player in the world on Monday, and he definitely deserves full recognition for that. However, the No. 1 ranking is the last 52 weeks: winning a Grand Slam is more about being the man of the moment. With a fourth-round loss at Wimbledon, an early loss in Montreal, and a quarterfinal loss in Cincinnati it's clear that Nadal is not at the top of his hard-court game.

With Nadal, there's also a question of how he has done at Flushing Meadows since last winning the tournament. Third and fourth-round losses the last two years running aren't anything that inspires confidence. The US Open was never really his bread and butter, it was the last major that he won, and he looks overrated heading into this year's event priced at +250 with bet365.

Keep in mind that when he won the event in 2013, it was obvious that he was going to win it as he'd won both Montreal and Cincinnati outright that year.

With Roger Federer, the reason to be skeptical is certainly less obvious. But when one looks at Federer's Montreal draw, what did he do? The Swiss Maestro 'survived' a cushy draw that included Peter Polansky, David Ferrer (who Federer is 17-0 against), and Robin Haase before losing comprehensively to Alexander Zverev.

In the Montreal final, Federer certainly didn't pass the eyeball test. Some (Annabel Croft) have suggested that Federer had a back issue in the final.

How about Zverev as the favorite?

Alexander Zverev lost in the Cincinnati second round, but there's not much to read into that loss. Zverev was playing in his third tournament in three weeks having won titles in the previous two. Players simply don't do well in the third tournament when their schedule is that dense. Zverev winning Washington and Montreal, through Federer in the final of the latter tournament, should make the German the favorite. That is especially the case given that Murray is all over the map right now with his health. When he withdrew from Cincinnati, it was only about a day after the tournament affirmed that he would be the top seed in the draw.

Surely he, along with former-champ Marin Cilic and Milos Raonic, has to be considered questionable to do well at the 2017 US Open at this point.

There is some good reason to be skeptical of Zverev because he has not yet arrived in any Grand Slam. His fourth-round appearance at Wimbledon 2017 is his best major result. However, all currently-established players were once unproven, and if anyone is to emerge in this time on tour when so many top players are injured, it should be Zverev. That he was able to win ten matches over a short period in Washington and Montreal shows that his fitness is up to the task of winning a Grand Slam.

US Open very wide open?

But in the end, it simply might be that there is no heavy favorite heading into the US Open.

Zverev is still just 20 years old, Nadal is off-form on cement, and Federer didn't seem like he could take what Montreal dished him. Murray has his hip and Cilic has been missing since Wimbledon. Looking down the list of favorites, Dominic Thiem simply isn't that great on cement while Juan Martin del Potro is not playing anywhere near a Grand Slam winning level. Milos Raonic has his wrist problem while Grigor Dimitrov is a tough read. The Bulgarian is in the Cincinnati semifinals, but maybe only because the draw wasn't well contested. The 2017 US Open might produce a shock champion just as Cincinnati is about to add a major title to a peripheral players' resume. It looks like a time on tour where being well rested and in good physical condition counts for a lot. Anyone that fits that description with a top-25 ranking could do big damage at Flushing Meadows.