Injury cruelled Stosur’s hopes of a fifth quarter-final appearance in eight years as Latvian young gun Jelena Ostapenko soared to a watershed 2-6 6-2 6-4 win over the former Roland Garros runner-up overnight, Australian time.

Unable to recover after requiring a medical time-out for a hand issue after dropping the second set, Stosur bowed out after one hour and 58 minutes of tension on Court 2.

A former Wimbledon junior champion, 19-year-old Ostapenko will face 11th-seeded ex-world No.1 Caroline Wozniacki on Tuesday in her maiden grand slam quarter-final, while Stosur will be left to ponder what might have been.

The 33-year-old had held Australia’s No.1 ranking since usurping Casey Dellacqua in October, 2008, but has now relinquished top spot to Daria Gavrilova.

It’s a tough changing of the guard for Stosur, with the Queenslander defeating Gavrilova in the final of the Strasbourg International eight days ago before the Moscow-born 23-year bombed out in the first round at Roland Garros.

Gavrilova remains alive in the women’s doubles and will team with Russian Anastasia Pavlyuchenkova to try to stop the run of Dellacqua and fellow Australian Fed Cup teammate Ashleigh Barty when they clash in the third round tonight.

Stosur had beaten Ostapenko in three sets in their only previous meeting, on a hard court at last year’s Rio Olympics, and looked on track early to breeze to another victory over the world No.47.

It quickly became apparent that Ostapenko’s unorthodox service was the Latvian’s major vulnerability.

Stosur broke her immediately with a booming forehand return, then struck again two games later to race to a 4-0 lead after only 13 minutes.

But three double-faults and a framed forehand were the first signs Stosur was struggling physically as the Queenslander gifted Ostapenko a break back.

Ostapenko was unable to hold, though, as Stosur continued to pounce on anything short to seize a 5-1 advantage.

Stosur faltered again before closing out the opening set after 34 minutes with a fourth service break.

Stosur had a chance to break Ostapenko early in the second set and snare a 2-0 lead.

But the one-time US Open champion failed to convert, the foothold into the match proving the only invitation Ostapenko needed as she reeled off five successive games to draw level at a set apiece.

Applying an ice pack on her serving hand during changeovers, Stosur dropped serve in the fifth game of the deciding set and, despite conjuring four break-back chances, she couldn’t find a way back into the contest as Ostapenko clinched the most significant win of her career.

-AAP