Will Serena slump after acing the Euro Slams?

Canada's newly minted tennis fans are quickly learning that life in the big leagues for homegrown paragons such as Eugenie Bouchard and Milos Raonic isn't all fashion magazine cover shoots and fame so big that your hair has its own Twitter account.

On the eve of the high-octane Canadian Open combined (aka, the Rogers Cup), the Francophone star Bouchard -- a 2014 Wimbledon finalist once ranked as high as No. 4, now down to No. 25 -- remains mired in a horrific slump. She has also been treating an abdominal injury.

Raonic, from Anglophone, Toronto, is treading water in the top 10, seemingly unable to make that final major breakthrough at a Grand Slam or Masters 1000 event. He was sidelined after Wimbledon with lingering foot problems and will make his return in the men's tournament.

The men and women alternate annually between Toronto and Montreal. And after a few weeks of beach tennis in Sweden, Alpine clay-court tennis and another John Isner serving exhibition in Atlanta, fans are ready for some gravitas with their inside-out forehands. All 25 top women are entered in Toronto. Roger Federer is the only top man missing from the field in Montreal, which is one of the prestigious Masters 1000s.

Here are five additional storylines to watch as this combined event unfolds:

1. Serena Williams will try to complete a Grand Slam in three weeks' time at the U.S. Open. She opens her bid in Toronto, coming off a few weeks during which she rested a sore elbow. It will be interesting to see how the elbow is doing and how Williams handles the hype and pressure. And also to see whether anyone can capitalize on the distractions to plant a seed of doubt in her mind.

2. If Rafael Nadal is going to salvage his year and get earn back his Big Four status, Montreal would be a good place for him to start. He has won this tournament as often as any other hard-court Masters 1000 (three times), and he's coming off a win in Hamburg.

3. Williams and the other veterans on the WTA Tour are sitting on a powder keg of developing talent. Sloan Stephens and, more recently, Eugenie Bouchard haven't found it quite so easy to establish themselves near the top, but a host of other young pros are waiting in the wings. They include Wimbledon finalist Garbine Muguruza, Madison Keys, Belinda Bencic, Caroline Garcia, Katerina Siniakova, Ana Konjuh and others. They may start an avalanche that sweeps away veterans such as Svetlana Kuznetsova, Samantha Stosur, Ana Ivanovic and Jelena Jankovic. Could this be the week it begins?

4. Can No. 4 Stan Wawrinka continue to build on his success in 2015? Any lingering suspicion that the 30-year-old Swiss wasn't cut from Grand Slam timber despite his win at the 2014 Australian Open was refuted -- with an exclamation point -- by Wawrinka's win against Novak Djokovic in the French Open final last June. And there certainly was no shame for Wawrinka losing 11-9 in the fifth versus Richard Gasquet in the quarterfinals of Wimbledon.

5. American men, led by John Isner, are playing well. But they face a fundamental challenge: They need to ratchet up those big games when it counts most -- in big tournaments. In addition to Isner, who won Atlanta for the third time running a week ago, Jack Sock and Steve Johnson have done some excellent work this year.

Sock is just 22 years old and up to No. 37. Johnson, 25, is No. 55, but he's one of those guys who seems to really know how to turn experience into gold. They ought to be at their best on North American hard courts in the weeks to come. Let's see if they can step up.