British number one Laura Robson has revealed that a mystery wrist injury forced her to pull out of the Rogers Cup just hours before her first-round match with Yanina Wickmayer.

Robson felt her wrist give way during a morning practice session in Montreal, leaving her with no choice but to withdraw from the prestigious tournament at short notice.

The 19-year-old remains hopeful of playing in the US Open later this month, with a scan due later today to determine the extent of her wrist injury.

She told Tennis TV: "Well I practised this morning and everything felt fine and then I hit one routine backhand and felt something go in my wrist.

"We're not sure what it is yet, I've got an MRI scan later today. The physio team and I did everything we could to try and get on court but I just wasn't able.

"I don't know what's going on until the MRI but hopefully I'll be able to play next week and in the next few lead-up tournaments to the US Open."

The Montreal Masters got underway without Robson earlier today, in an opening day featuring Sloane Stephens and Kei Nishikori.