Just two days into the Ashes series and DRS has already played a major part, with both England and Australia benefiting and suffering at the hands of cricket's review system.
But how does a batsman really decided if to use a review? How does the fielding captain truly know if it was LBW or not? Are there team orders to save reviews for their star players?
Well England's Ashes 2015 series winners, Yorkshire batsman Adam Lyth and Gary Ballance, have given an exclusive insight to sportinglife.com into the system and how these decisions are made.
Watch to learn more about DRS and the huge role it will play in defining the 2019 Ashes series.