5. Ruslan Provodnikov
‘The Siberian Rocky’ currently operates at light-welterweight but has competed at 147lbs – most prominently in his enthralling world title clash with Timothy Bradley in 2013. Trained under Freddie Roach, the teak-tough 31-year-old guarantees excitement and his constant pressure would prove a stern challenge for Brook. Never one to shy away from a fight, Kell’s resolve would be tested by Provodnikov and with both men holding notable power, there would be drama along the way and potentially some trips to the canvas. Bradley went life-and-death with Provodnikov, so if Brook were to beat him more convincingly, his stock would rise considerably.