Ten-year-old singing sensation Maria Aragon of Winnipeg performed with her idol, outrageous chart-topping singer Lady Gaga, during a sold-out concert in Toronto on Thursday night.

The grade-school student, who caught Gaga's attention after posting a cover of Born This Way online, sang the American pop star's hit single with her about an hour into the show at the Air Canada Centre.

Maria strode out dressed in shiny black pants, a pink shirt and a white hat.

"I'm really excited that Maria is here today, because Maria represents what this song is all about," Gaga said .

"It's all about the next generation and the future, and no more divisiveness."

The 10-year-old sat on her idol's lap at the piano and the pair performed to a roaring, cheering crowd.

Gaga, who called Aragon "Lady Maria from Winnipeg," was in tears after the young performer left the stage.

"Lady Maria really belted it out," CBC reporter Sheila North Wilson said from the concert, which started more than an hour late. "The crowd loves her."

Maria Aragon says it was 'so great' to sit at the piano with Lady Gaga. She says Gaga's Toronto fans made her feel welcome onstage. (CBC)

After the duet, Maria thanked her family and friends for their support before heading offstage.

"I'm just really grateful to all of you."

The young singer popped out again during the encore, joining Gaga for a final dance. At a news conference after the show, Aragon said the dance was spontaneous and hadn't been rehearsed.

"She got me all pumped up and she made me so comfortable, so I just started dancing," Maria said. "It was for the crowd."

The self-taught musician said she was comfortable onstage, but the whole experience was a bit overwhelming.

"Lady Gaga is really big and she's so amazing," the Winnipegger told reporters after the show. "Being supported how she was supported up there made me feel really great."

Viral sensation

Maria's catapult to fame began last month after she posted to YouTube a simple video of herself singing and playing keyboard to Born This Way.

Gaga herself viewed the video and shared it with her millions of Twitter followers, noting: "Can't stop crying watching this. This is why I make music. She is the future."

A Canadian radio station also put the young girl in touch with her idol, who admitted she had been having a bad day until Maria's video brightened her mood.

Along with singing a brief portion of Born This Way with Aragon on air during the radio interview, Gaga invited the youngster to join her for Thursday's Toronto gig.

The grade-schooler soon became a media darling, interviewed by a host of Canadian and U.S. outlets, including for appearances on Ellen and Good Morning America. Her YouTube video has logged more than 17 million hits.

After the concert, Maria thanked Lady Gaga and all the people who helped arrange Thursday night's performance — including hometown supporters.

"I was so proud to represent Winnipeg," she said after the show. "I had a lot of support from there."

With files from Sheila North Wilson