Tuesday's "America's Got Talent" live round could not have been more exciting as the 12 acts took to the stage in heated competition.

Siro-A, the Japanese dance crew, opened the show by combining electronic music and eye-popping graphics that included the faces of judges Howie Mandel and Howard Stern. The performance brought the entire audience of Radio City Music Hall to its feet.

Alondra Santos, 13, used her incredible voice to belt out a Flamenco-style song with a dance that amazed. "I am so glad we called you back," Mandel said. "I couldn't stop moving my biddie-biddie-bum-bum."

Flaming-haired contortionist Vita Radionova used mirrors to create fascinating optical illusions for her performance. Her extreme physical flexibility defies the human body's normal capability of movement.

Fan favorite Triple Threat did their rendition of Destiny's Child's "Say My Name," which garnered a buzz from Stern and Mel B. "All of the charm went out of the act tonight," Stern said. The buzzers could spell trouble for the boy band.

The Gentlemen, two hip-hop dancers ages 9 and 12, entertained with their break-it-down skills, but it wasn't their best performance. "I just saw a lot of repeated steps," Mel B said. "You're still good -- really good."

Piff the Magic Dragon created a "Game of Thrones" reenactment with Mandel's help. Mandel had to guess which box Piff's dog was in before the pup was catapulted to the ground and then beaten. It was strange. Although the dog was not harmed, the stunt did not go over well. "I don't know," Heidi Klum said. "I did not enjoy [it]."

Country papa Benton Blout sang a touching song called "Say Something" while strumming his guitar as the stage was washed in blue light. It was a great performance, but will it be the most memorable for voters?

Ballroom dance champions Craig and Michelline danced to "Tainted Love" which amazed. "I like this act and I've liked it all along," Stern said. "If I was sitting at home and had to vote for a dance act, I love your pure strength."

Stand-up comedian Drew Lynch proved he can come up with hilarious material on a whim. He made fun of Piff and his dog stunt to everyone's amusement. "You check every box for me. ... You are triumph in the face of adversity," Mandel said.

Show Project performed their best gymnastics and acrobatics to Nick Jonas' "Chains." It was a riveting, contemporary performance that one might see in an edgy Hollywood nightclub. "You bring an edge and a hipness to gymnastics," Mandel said.

British ventriloquist Paul Zerdin surprised everyone when he stepped away from sidekick and dummy Sam, who was left to his own devices. It was remarkable and fun. "Favorite act of the night," Mandel said.

Samantha Johnson was the night's final contestant. Her performance was powerful and moving, like her life story. She sang "California Dreaming" which received a standing ovation. She could very well beat Santos in the singing competition.

Watch the "America's Got Talent" live voting results from round one Wednesday, Aug. 12 at 8 p.m. ET on NBC.

Did Triple Threat deserve to get buzzed? Could Samantha win over Alondra? Who are you worried will be sent packing Wednesday night? Share your thoughts and who you'd like to see win in the comment section below.