The second half of the North American Masters 1000 doubleheader is starting, even as the Rogers Cup still is unfolding in Canada.
The Cincinnati field features fewer withdrawals from the original acceptance list than in Canada, where 11 of the 44 at the entry deadline ended up pulling out. Add in Tomas Berdych and Gilles Muller, who withdrew after the draw, and that’s a very unlucky 13.
As well, the Montreal qualifying field was thin – the cut-off was No. 412, and there were four alternates (Canadian players who just happened to be around).
Some of the same highly-ranked absentees persist in Cincinnati: Andy Murray, Novak Djokovic, Stan Wawrinka, Marin Cilic. But only seven of the original entrants are out.
Those include Frenchman Lucas Pouille, who lost to American Jared Donaldson in the first round of singles in Montreal but played well through two rounds of doubles with countryman Jo-Wilfried Tsonga.
The qualifying cutoff in Cincinnati was No. 219. But still, there were three alternates – including two doubles specialists.
The big question will be, how will the big guns fare after so many made premature exits in Montreal?
Juan Martin del Potro defeated John Isner, but went down in straight sets to the star of the week, 18-year-old Canadian teenager Denis Shapovalov.
Kei Nishikori lost a tough one to Gaël Monfils in his first match.
Milos Raonic, the No. 6 seed in his home event, was granted an extra day to play his first match because of a wrist injury. But the effects were clear, as he was defeated by Adrian Mannarino.
Rising star Alexander Zverev has played a lot of tennis the last two weeks. He won in the heat in Washington, D.C. (and played doubles)., and is in the semi-finals in Montreal.
Dominic Thiem lost his first match (and didn’t appear to be in much better spirits in Cincinnati this weekend).
None of the players truly want to peak in Cincinnati, with two weeks still to go before the final Grand Slam of the season.
No. 1 decided in Cincinnati
Rafael Nadal is less than 200 points behind Murray for the No. 1 spot as the week begins. He reached the third round in Cincinnati a year ago; that’s 90 points that will fall off on the Monday after the event concludes.
Federer, depending on his result in Montreal, will be right behind Nadal. And he didn’t play Cincinnati last year (or anything after Wimbledon).
Here’s how the head-to-head race for the new No. 1 will play out.
If Federer wins the Rogers Cup, he’ll stay ahead of Nadal as long as both reach the same round. To take over No. 1, Nadal would have to reach at least the quarter-finals to start, and go one round further than Federer.
But if Federer loses the Montreal final, his task gets exponentially tougher. He would have to reach the semis just to stay ahead of what Nadal already brings to the table without even winning a match.
If Federer gets to the Cincinnati final, Nadal would have to lose in the quarters for Federer to be No. 1. But, if Federer wins Cincinnati, he would become No. 1 no matter what Nadal does.
Those are the business-end scenarios. Obviously, either could lose at any stage.
(Please send any corrections to this math to [email protected])
Potential round of 16s
A lot has to happen, but here’s how the Cincy draw shakes out on paper.
 Rafael Nadal vs.  Gilles Muller
 Jo-Wilfried Tsonga vs.  David Goffin
 Dominic Thiem vs.  Sam Querrey
 Kei Nishikori vs.  Pablo Carreño-Busta
 Milos Raonic vs.  Roberto Bautista-Agut
 Alexander Zverev vs.  John Isner
 Grigor Dimitrov vs.  Tomas Berdych
 Roger Federer vs.  Jack Sock
It’s hard to effectively determine which half is tougher, because so few of the seeded players are playing well.
First-round matches to watch
With the 56-player draw, the top eight seeds have a bye.
Still, some compelling first-rounders
* David Goffin vs. Nick Kyrgios
* Tomas Berdych vs. Juan Martin del Potro
*Steve Johnson vs. David Ferrer (a grinder’s delight)
*Diego Schwartzman vs. Karen Khachanov