You only have to look at last year’s Rogers Cup semifinalists – the Williams sisters, Agnieszka Radwanska, and Ekaterina Makarova – to be reminded what a huge tournament it is on the WTA calendar. Venus upset the odds in 2014 by beating Serena 6-7 6-2 6-3 and Radwanska overcame Makarova 7-6 7-6 before thrashing the American 6-4 6-2 in the final.

But it’s difficult to know what to expect this year. Serena is set to play but may at some point withdraw due to a persistent issue with her right elbow, Maria Sharapova has already pulled out with a leg strain, and Petra Kvitova has had a decent year so far but never seems far away from a shock loss, as her third-round defeat to Jelena Jankovic at Wimbledon demonstrated.

As for last year’s champion from Poland, she has had a relatively poor 2015 overall up to this point, but Radwanska has been on a steady upward curve ever since the grass season began. She reached the semifinal at Nottingham, losing to Monica Niculescu, and then the final at Eastbourne, where she lost to Belinda Bencic.

Radwanska then produced a superb run at Wimbledon, beating Ajla Tomljanovic, Jankovic, and Madison Keys on her way to an entertaining semifinal with Garbine Muguruza, which she lost 2-6 6-3 3-6. The Pole almost lost her first match of the US Open Series against Misaki Doi at the Bank of the West Classic in Stanford, but she found her form and reeled off 12 games in a row to win 1-6 6-2 6-0. Radwanka then lost a stunning quarterfinal night match with Angelique Kerber 6-4 4-6 4-6.

Radwanska should take confidence from that performance, but she has a tough draw to contend with in Toronto. She could even struggle in her first match, particularly if it is Anastasia Pavlyuchenkova who prevails over Zarina Diyas in round one. The Russian has been in excellent form in the last two weeks, reaching consecutive semifinals in Baku and Washington, and she will fancy her chances of causing an upset.

If the Pole does clear the first hurdle, awaiting her in the third round will be Sloane Stephens, Dominika Cibulkova, Alize Cornet, or Carla Suarez Navarro, and then she could face Simona Halep, Caroline Garcia, Jankovic, or Kerber (again) in the fourth round.

On current form, Kerber has to be the favorite to emerge from this quarter of the draw. She played some excellent tennis to reach the final of the Bank of the West Classic, and she has already won three titles this year, making her a very difficult woman to beat right now.

When Halep won Indian Wells in March and then pushed Serena to three sets in Miami immediately afterwards, she looked set to have a fantastic season. But she has been lackluster since then, and few people will expect her to shine in Toronto. It is up to the No. 2 seed at the 2015 Rogers Cup to step up and remind everyone how good she is.

Meanwhile, if Serena’s elbow holds up, she should breeze through potential match-ups with Flavia Pennetta and Andrea Petkovic en route to a likely quarterfinal against either Lucie Safarova or Karolina Pliskova, who has now reached as many WTA finals as the American in 2015 after Stanford.

The 21-time Grand Slam champion is seeded to face Caroline Wozniacki in the semifinal, but the Dane has injury problems of her own, and her calf injury already contributed to a second-round straight-sets loss to Varvara Lepchenko at the Bank of the West Classic.

Wozniacki will face either Eugenie Bouchard or Belinda Bencic in round two. The Canadian locals will be desperate to see their great WTA hope return to form and set up that clash. However, given Bouchard’s well-documented struggles and Wozniacki’s fitness worries, the 18-year-old Swiss should view this as a fantastic opportunity to reach the third round.

The winner of that segment can probably look forward to a contest with either Venus Williams or Sabine Lisicki, and if Bencic plays the German she will doubtless be hoping Lisicki does not serve a world-record number of aces against her again – as she did in Birmingham.

Win that, and a quarterfinal against Makarova likely awaits. It could be against fifth seed Ana Ivanovic instead, but, aside from reaching the French Open semi-final and the Brisbane International final, the Serb has had a poor 2015, and the in-form Russian will be the heavy favorite.

The other quarter of the draw is set up very intriguingly, with Kvitova seeded to meet Muguruza in the last eight. The Spaniard might have to beat the ever-improving Timea Bacsinzsky to reach that stage, while Kvitova has a very difficult second round to negotiate against either Victoria Azarenka or Elina Svitolina. Azarenka pushed Serena close at Wimbledon, while Svitolina, 20, demonstrated her credentials with an excellent run to the Stanford semifinal.

Fitness permitting, Serena Williams will be very confident of taking her place in the semifinals at the end of the week. The race to face her in the last four is definitely wide open, especially if Wozniacki’s calf injury holds her back. Will Serena face sister Venus? Might Makarova reach the semis again? Will Lisicki step up? Or can Bencic continue her impressive rise by blazing past Bouchard, Wozniacki, Lisicki or Venus, and Makarova?

In the other half, the second round between Kvitova and either Azarenka or Svitolina will probably decide one quarterfinalist, and the victor will expect to battle it out with Muguruza for a place in the last four. Another Radwanska versus Kerber clash in the quarter-final to decide the other semifinalist seems likely, and it could provide great entertainment once again. If, and it is a big if, Halep regains her form, she could prevent this clash.

With the possible exception of Serena, who will be the favorite for the US Open if she is fit, this week in Toronto is vital for all the women competing. They will be keen to find or maintain form ahead of the year’s final Grand Slam and earn a hefty helping of ranking points in the race to Singapore.