But those principal men provide lots of thrills , particularly when they are Marcelo Gomes ( replacing an injured Maxim Beloserkovsky as Conrad ) , Sascha Radetsky ( as Birbanto , the friend who ultimately betrays him ) , Angel Corella ( the slave Ali , whose turquoise abs-baring costume and passionate solo were immortalized by Nureyev ) and Herman Cornejo ( as Lankendem ) .