At this time last year, Camp Nou supporters showered Dembele with boos as his contract extension talks came to a standstill. Fans jeered when he touched the ball and whistled when he misplaced a pass, even as Xavi pleaded with them to be nice.
With just a couple of months left on his deal, it appeared Dembele would leave Barcelona a villian.
But on Wednesday night, the crowd screamed Dembele's name as he turned in a match-winning performance for the Blaugrana, starring throughout as they beat Real Sociedad 1-0 to advance to the Copa del Rey semi-final. They ended the visitors' club record nine-game winning streak in the process.
Dembele, now under a new contract signed in a dramatic U-turn last summer, came close to scoring after 20 minutes, curling a shot just outside the post.
Real Sociedad midfielder Brais Mendez then crushed a spirited response from his team to that early warning when he was sent off for a dangerous tackle on Sergio Busquets just before half-time.
And Barca, with the help of their French winger, punished them shortly after the break. Dembele sprinted down the right channel and ran onto a perfectly weighted pass from Jules Kounde, before beating Alex Remiro at his near post for a 1-0 lead. Sociedad came close to an equaliser, with Alexander Sorloth firing over from close range, but the Blaugrana were otherwise relatively stable in a 1-0 win.
It all underlined a major turnaround for Dembele, who seemed so likely to leave Barcelona just a year ago and was slammed by many fans as a result. Injuries and up-and-down performances hadn't helped matters.
But he's been much better since that turning point, and Wednesday offered another look at his ability to be one of the world's best when healthy.