ADELAIDE, AUSTRALIA - DECEMBER 05: Steve Smith of Australia gestures to Nathan Lyon of Australia after calling successfully on the DRS for the wicket of Alastair Cook of England  during day four of the Second Test match during the 2017/18 Ashes Series between Australia and England at Adelaide Oval on December 5, 2017 in Adelaide, Australia.  (Photo by Mark Kolbe - CA/Cricket Australia/Getty Images)