Kevin Pietersen has promised to challenge England white-ball head coach Brendon McCullum in his new role as a specialist mentor to the team, saying it's precisely why he was brought in. Source: https://www.skysports.com/cricket/news/12040/13592509/kevin-pietersen-promises-to-challenge-brendon-mccullum-as-england-white-ball-head-coach-eyes-world-no-1-ranking