A rapper pal of British pop star Tulisa Contostavlos has pleaded guilty to supplying cocaine to an undercover journalist, on the eve of the pair's trial. The former N-Dubz star is accused of brokering a deal for half an ounce of the drug by arranging a meeting between the reporter and Michael Coombs, who is known professionally as Mike GLC, in May last year (13). Contostavlos denies the charge, but at the start of their joint trial in London on Monday (14Jul14), Coombs changed his plea and admitted being concerned in the supply of Class A drugs. He will be sentenced at the end of Contostavlos' trial, which is due to open before a jury on Tuesday (15Jul14). The pop star, of Friern Barnet, north London, denies being concerned in the supply of cocaine.