Madonna Is 'Feeling Strong' and Back in Rehearsals for Her 'Most Ambitious Tour Ever': Source (Exclusive)

"She's so happy to be back onstage," a source tells PEOPLE exclusively of the superstar, who was hospitalized in June for a bacterial infection

The Queen of Pop is ready to reign again.

After being hospitalized in late June for a "serious bacterial infection," Madonna is back at work and gearing up for the launch of her Celebration Tour, a source tells PEOPLE exclusively.

"She returned to rehearsals last Monday. She's so happy to be back onstage and is feeling strong. She's working closely with her longtime collaborators, Jamie King and Stuart Price, to put the final touches on the show," says the source, adding that the run of shows is the icon's "most ambitious tour ever."

Late last month Madonna shared photos from a vacation to Lisbon, where she spent some downtime with loved ones before heading back for rehearsals.

Related: Madonna Shares Birthday Message After Turning 65: 'It's Great to Be Alive'

"She enjoyed her birthday in Lisbon with all her kids and close friends. Now she's back in work mode and focused on the tour," says the source. "This is where she thrives. She loves being back in a creative environment."

The superstar will head across the pond next month to kick off her tour with four sold-out shows at the O2 Arena in London, followed by stops in Copenhagen, Barcelona, Paris, Milan and more.

Wrapping up 2023, Madonna will launch the North American leg of her tour with three shows at Brooklyn's Barclays Center and two concerts in Washington before returning to the stage in 2024.

Related: Madonna Thanks Her Kids for Their Support After Her Hospitalization: 'It Made All the Difference'

Two days after turning 65 on Aug. 16, Madonna — who's mom to Lourdes Leon, 26, Rocco Ritchie, 23, David Banda, 17, Mercy James, 16, and 11-year-old twins Stella and Estere — shared a compilation of clips from her time in Lisbon set to her hit "Vogue."

"It's great to be Alive ... and Amazing to Be able to put on my dancing shoes and Celebrate my Birthday!" she wrote on Instagram. "I'm So Grateful. Thank you Lisbon and to all who made it possible!"

Madonna first announced the Celebration Tour in January, telling fans the concerts would commemorate the 40-year anniversary of her career and pay tribute to New York, where she first launched to stardom.

"I am excited to explore as many songs as possible in hopes to give my fans the show they have been waiting for," she said in a press release at the time.

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