Jwala caused a major upset in the Coolmore Nunthorpe Stakes at York.
The least-fancied of three runners for trainer Robert Cowell, the 40-1 shot was smartly away in the hands of Steve Drowne and was disputing the running from the start of the five-furlong contest.
South African star Shea Shea and Ireland's Sole Power were both thrusting at the finish, but Jwala held on by half a length.
It was a particularly sweet outcome for Drowne, who only returned to race riding earlier in the year after he suffered two blackouts last spring.
He said: "Everyone knows my problems last year, but you need a horse like this to bounce back.
"You just need to land one like this and it gets you back.
"She's a fabulous filly."
Old rivals Sole Power and favourite Shea Shea shadowed each other throughout, with Johnny Murtagh aboard Sole Power keen to keep Frankie Dettori in his sights.
The two made their respective moves a furlong out, but Jwala was not for catching.
Shea Shea finished second, a nose ahead of Sole Power.
Jwala won a Listed event over the course and distance on her penultimate start last month, but then finished last of 17 behind a number of reopposing rivals at Glorious Goodwood following a tardy start.
Jockey Drowne added: "She had a tough time last time. She got upset last time and knocked herself silly. She didn't go a yard and tailed off at Goodwood.
"Thank God they found a reason - she'd nearly fractured an eye socket - and she's bounced back here.
"She travels very well during the race, almost too well, but she kept on going."
Trainer Robert Cowell was thrilled with the outcome.
"I'm speechless," he said.
"She's a grand filly and only finished a length behind Sole Power last year as a three-year-old at Doncaster in a Listed race.
"She's come on leaps and bounds, she's ultra tough and she's got a really high cruising speed.
"At Goodwood last time she fractured her eye socket, which only came to light later on, but she's come back."