The men’s singles event has been held since 1881 and is taking place in Toronto, with the final set to be held at the Aviva Centre, while the women’s singles event started in 1892 and is being hosted in Montreal, with the final due to be hosted at the IGA Stadium.

The Association of Tennis Professionals (ATP) Tour Masters 1000 and the Women’s Tennis Association (WTA) 1000 tournaments alternate venues each year at the annual event.

With the event last being held in 2019, the defending men’s singles champion is Spaniard Rafael Nadal, who defeated Russia’s Daniil Medvedev in straight sets in the final having also won the tournament in 2018.

Bianca Andreescu became the first Canadian to win on home soil since 1969 when the women’s singles event was held in 2019 following the retirement of American Serena Williams in the final.

Forty-eight players are involved in the men’s singles tournament, with the top 16 seeds receiving a bye to the round of 32.

World number two Medvedev is the highest seed, and could face a repeat of the 2019 final with number two seed Nadal in the opposite half of the draw.

He was beaten by Pablo Carreño Busta of Spain in the quarter-finals at the Tokyo 2020 Olympics, but has three career ATP Masters 1000 wins to his name.

Medvedev’s compatriot Andrey Rublev, ranked seventh in the world, is a potential semi-final opponent.

The world number seven lost to Greece’s Stefanos Tsitsipas in his maiden ATP Masters 1000 final in Monte Carlo earlier this year, and travels to Canada having won a mixed doubles gold with Anastasia Pavlyuchenkova at Tokyo 2020, but been eliminated from the men’s singles tournament in the opening round by Japan’s Kei Nishikori.

Tsitsipas could provide a strong challenge to Nadal’s bid for three-in-a-row in Toronto, and would leapfrog him in the world rankings were he to triumph.

Canada’s hopes for a first victory in this event during the open era rest on fifth seed Denis Shapovalov in the top half of the draw, and ninth seed Felix Auger-Aliassime and wildcard entry Vasek Pospisil in the bottom half.

Wimbledon semi-finalist Shapovalov is ranked 10^th in the world, while Auger-Aliassime - who turned 21 today - is the youngest player in the ATP world top 20.

Twenty-two year-old Casper Ruud of Norway has already won four titles this year with the sixth seed in the same half of the draw as Nadal, Tsitsipas and others.

Seventh seed Hubert Hurkacz of Poland won the first ATP Masters 1000 event of the year at the Miami Open in April, which was also his first such title - a potential quarter-final against Medvedev, who he knocked out of Wimbledon in July, awaits.

The other seeds are Australia’s Alex de Minaur, France’s Gael Monfils, Chile’s Cristian Garin and Italy’s Jannik Sinner in the top half, and in the bottom half Diego Schwartzman of Argentina, Roberto Bautista-Agut of Spain, Grigor Dimitrov of Bulgaria and Aslan Karatsev of Russia.

Australian Nick Kyrgios is one of three wildcard entries, while six players will progress through qualifying today.

World number one Novak Djokovic of Serbia has withdrawn to aid his preparations for the US Open as he seeks to become the first man since Rod Laver in 1969 to win all four majors in a calendar year.

Newly crowned Olympic champion and 2017 Canadian Open winner Alexander Zverev of Germany, Wimbledon finalist Matteo Berrettini of Italy, Switzerland’s Roger Federer and Canada’s 2013 finalist Milos Raonic are also among the absentees.

In the WTA 1000 women’s singles tournament, 56 players will take part, with the top eight seeds receiving a bye to the round of 32.

Belarus’ Aryna Sabalenka is the top seed.

The world number three suffered a second-round exit at Tokyo 2020 to Croatia’s world number 53 Donna Vekić, who is also in the top half of the draw.

However she reached the semi-finals of Wimbledon in July in the 23-year-old’s best Grand Slam performance to date, and has won four WTA 1000 titles, most recently the Madrid Open in May.

World number five Andreescu was 19 when she triumphed in Toronto and won the US Open later that year, but a knee injury and the COVID-19 pandemic meant she was out of action for 15 months, and she has suffered early exits from each of this year’s Grand Slams.

She retired from the Miami Open final against Australia’s Ash Barty earlier this year.

Andreescu begins her defence of her title as the second seed.

Olympic women’s singles bronze medallist Elina Svitolina enters the Canadian Open as the third seed, and won the event in 2017.

The world number six is in the bottom half of the draw.

Karolína Plíšková of the Czech Republic was runner-up at Wimbledon in her first Grand Slam final in five years.

The fourth seed is in the top half of the draw, and seeking a third title of the current WTA 1000 events and her first since the Italian Open in 2019.

The fifth and eighth seeds in the top half of the draw are Spain’s Garbiñe Muguruza, who won her second WTA 1000 event at the Dubai Tennis Championships earlier this year, and Belarus’ Victoria Azarenka.

Azarenka won 10 WTA Premier Mandatory or Premier 5 events before they merged into the WTA 1000 this year, her first success at the Miami Open in 2009 and most recently at the Cincinnati Masters in 2020.

The sixth and seventh seeds in the bottom half of the draw are Romania’s Simona Halep and the Czech Republic's Petra Kvitová.

Halep won the Canadian Open in 2016 and 2018 among eight WTA Premier Mandatory or Premier 5 titles.

She is returning to competitive action for the first time since May’s Italian Open, having missed the French Open and Wimbledon with a calf injury, and is one of five wildcard entries to the women’s singles tournament.

Kvitová suffered early eliminations from each of this year’s Grand Slams, but won this tournament in 2012 among 28 WTA titles - the most of any player at this year’s Canadian Open.

Among the other seeds are Kazakhstan’s Elena Rybakina, who lost the bronze medal match at Tokyo 2020, and Russia’s Anastasia Pavlyuchenkova, who won gold with Rublev in the mixed doubles in the Japanese capital.

The top two in the world in Barty and Japan’s Naomi Osaka have withdrawn, as well as fellow top 10 players Sofia Kenin of the United States and Iga Świątek of Poland and Olympic champion Belinda Bencic of Switzerland.

Men’s and women’s doubles tournaments are also being held.

Croatian duo Nikola Mektic and Mate Pavic are the top seeds in the 28-pair men’s tournament which also includes Rublev with Olympics men’s singles runner-up Karen Khachanov.

Thirty-two pairs will take part in the women’s doubles competition.

The Canadian Open begins the hard-court season in North America, with the US Open - the final Grand Slam of the year - set to start on August 30.

The men’s tournament has 1000 ATP ranking points on offer for the winner, with 900 WTA ranking points available for the winner of the women’s competition.