During  K-pop group 2PM's "World Tour GO CRAZY in Seoul" concert today, October 3, at the Jamsil Indoor Stadium, the idol group broke off into groups of two to perform for an audience of 7,000 people. 

The first unit to perform, Taecyeon and Chansung, caught the attention of fans with the dance sequence that showcased their abs during their performance of the track "Come Back," according to the Korean publication Osen Entertainment. 

"I hadn't been working out because I injured my arm, but I decided to get back into it for this specific peformance," stated Taecyeon after the dance sequence. 

Chansung added, "He made all the dancers work out too. He even paid for them to do it."

Taecyeon and Chansung also sang "To Say I Love You," which was written and composed by Chansung. 

Jun.K and Wooyoung, Nichkhun and Junho had their own stagetime as well. 

Jun.K and Wooyoung went into the hip-hop direction as they sang the track "Superman" while Nickhun and Junho followed up with a transition into the track "Love Is True."

The six members of the group, who returned after a year and 5 month hiatus, started off their concert with a performance of the track "Heartbeat." The boys continued with their hit single "Go Crazy," "Without U" and more, performing a total of 27 of their songs. 

Although the boys of 2PM successfully launched their world tour and have continued to top music charts since the release of "Go Crazy," they were initially concerned about whether their new concept would be accepted by the public or not.

"Producer Park tries to give us opportunities to mature musically. But I was worried that i might have to go back to old days (when Park produced their album) if the album fails," Jun.K told the Korean media outlet Financial News.