Canada's Kayla Cross and Ariana Arseneault are out of the National Bank Open after the first round.

Cross let a one-set lead slip away in a 4-6, 6-3, 6-2 loss to Kamilla Rakhimova of Russia on Monday afternoon.

The 20-year-old from London, Ont., who's ranked 151st in the world, fell to the 62nd-ranked Rakhimova in one hour 55 minutes on the hard court at IGA Stadium. It was their first career meeting on the WTA Tour.

Later in the afternoon, Arseneault of Richmond Hill, Ont., lost 6-4, 6-2 to Japan's Naomi Osaka.

Osaka, a former world No. 1, meets Russia's Liudmila Samsonova in the next round.

In the evening, local favourite Eugenie Bouchard will begin her final run in professional tennis against Colombia's Emiliana Arango. The 31-year-old Bouchard, a former world No. 5, recently announced she would retire after her hometown event.

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Ahead of retirement, Eugenie Bouchard praised for opening door for Canadian tennis players

Eugenie Bouchard, who grew up in Westmount, Que., is competing in her last tournament before she retires, finishing off her career at home.

Carson Branstine, who grew up in California but represents Canada through family ties in Toronto, takes on Greece's Maria Sakkari in the final match of the night.

Toronto's Victoria Mboko, Bianca Andreescu of Mississauga, Ont., and Vancouver's Rebecca Marino advanced to the second round with wins Sunday.

Andreescu's status for the remainder of the tournament is unclear after hurting her left ankle on match point Sunday night against Czechia's Barbora Krejcikova.

Martin swept on men's side in Toronto

Canada's Dan Martin fell 6-3, 6-0 to Spain's Jaume Munar in opening-round action in Toronto.

The 26-year-old Martin made it into the main draw as a qualifier after defeating Japan's Taro Daniel in three sets on Saturday.

Munar, ranked 51st in the world, fired six aces without a double fault in the one-hour, 10-minute match. He also broke on five of his 10 chances while winning 86 per cent of his first-serve points.

The Spaniard will next face 14th-seeded Francisco Cerundolo of Argentina.

Later Monday, Liam Draxl of Newmarket, Ont., plays Pablo Carreno Busta of Spain, and Alexis Galarneau of Laval, Que., is set to face Arthur Rinderknech of France.