Usher and Chris Brown were seen allegedly having an argument in the Skate Rock City roller rink in Las Vegas, RadarOnline.com has learned.

Video footage surfaced online from Friday night, May 5, showing the two R&B artists talking up against the railing of the roller-skating rink when Brown appeared to shove Usher aside as he skated off into the crowd.

The two were there to celebrate the Go Crazy singer’s 34th birthday.

Earlier in the night, the two were seen laughing with one another as Brown’s cartoonishly large cake was presented to him.

The freshly 34-year-old singer also posted, “I better get Cinco de fk’d tonight,” on Instagram before the party.

Eyewitnesses at the event claimed that the birthday boy had allegedly attempted to talk to Teyana Taylor, who was sitting on a bench outside the rink. The source further alleged that Taylor was ignoring Brown and Usher rolled in to try to talk with him.

According to the eyewitness, Brown reportedly told the crew he was with that they were leaving after the short confrontation. As soon as the rapper left the building, Usher was said to have rushed to take his skates off and ran after him.

One report alleged that the 44-year-old R&B singer went behind a string of charter buses parked in the lot where Brown and his crew were and later emerged from the parking lot with “a bloody nose.”