Pep Guardiola thinks the Champions League needs to introduce V-A-R after a controversial penalty marred Manchester City's 6-nil victory over Shakhtar Donetsk.
Gabriel Jesus started a hat trick with a farcical spot kick, awarded after Raheem Sterling went down unchallenged.
The result puts City on the verge of qualification for the knock out stage.
They would have gone through had Hoffenheim not scored a late equaliser in the other Group F at Lyon.
Guardiola says controversial incidents highlight the need for technology to help officials.