K-Pop starlets T-ara N4 are probably grateful for Chris Brown's support, but, like most things involving Brown, it comes with a price. That price for the girl group? Breezy interrupting one of their performances ... to promote himself.

On May 26, the girls opened up for Brown in Las Vegas, and he crashed their performance to plug his new single, 'They Don't Know.' "My next single featuring Aaliyah, called 'They Don't Know,' it's featuring Aaliyah ... and y'all have showed me so much love, we're gonna play it for you today," Brown said.

It appeared that there was simply a mix-up somewhere: Brown thought they were surprising the crowd with by playing the track, but it surprised T-ara too. The girls were visibly miffed and confused. Brown regained his footing, stammering, "But we gon' play it after the girls do their thing!"

The music started up again, including the vocals for T-ara N4 ... but the girls weren't singing yet. Yikes!