Kaia Kanepi moved into the second round of the National Bank Open on Tuesday, advancing past former World No.1 Naomi Osaka 7-6(4), 3-0, ret. Osaka was forced to retire due to a back injury.

“I felt my back from the start of the match, and despite trying my best to push through it I just wasn’t able to today," Osaka said afterward. "I’d like to pay credit to Kaia for playing well and want to wish her all the best for the rest of the tournament.”

It was an unfortunate end to an anticipated match between two exceptional ballstrikers. In their only prior encounter, Kanepi edged Osaka 7-5 in the third set in the third round of the 2017 US Open.

Nevertheless, Kanepi has picked up her fifth win in her last six matches. The 37-year-old veteran made a run to her 10th career singles final in Washington, D.C. last week. Former Top 15 player Kanepi has risen to World No.31 in this week's rankings, which is her highest position since 2014.

Osaka dropped serve at love to fall behind an early break at 3-2, and she took a medical time-out two games later. But after that, Osaka forced more errors from Kanepi and pulled back into the first set, including saving a set point at 6-5 with a forehand winner.

In the tiebreak, Kanepi grabbed a pivotal mini-break for 5-4 via a huge service return. A forehand winner lined up Kanepi’s second set point, which she converted after a long Osaka rally forehand. Kanepi then charged through three games of the second set before Osaka retired from their clash.

Noted upset specialist Kanepi, who has ten career wins over Top 10 players at Grand Slam events, will tussle with a Top 10 player in the second round: No.8 seed Garbiñe Muguruza of Spain. 

Kanepi and Muguruza have a 1-1 head-to-head. Muguruza defeated Kanepi in the first round of the 2014 Australian Open, but Kanepi got her revenge this year when she earned her most recent Top 10 win in a first-round upset of Muguruza at Roland Garros.