World Cup ready to showcase Day of the Jackal

FILE PHOTO: Rugby Union - Autumn Internationals - England v New Zealand - Twickenham Stadium, London, Britain - November 10, 2018 England's Sam Underhill runs in to score a try which is subsequently ruled out after a referral to the TMO Action Images via Reuters/Andrew Boyers

LONDON (Reuters) - Rugby's clampdown on high tackles is changing the approach to the breakdown, swinging the advantage to ball-stealers and, say players and coaches, making the "jackal" an even more essential weapon for any World Cup pretender.

The battle for the ball at the breakdown - what happens in the immediate aftermath of a tackle - has always been a fundamental part of the sport but increasing player welfare concerns are now subtly changing that critical theatre of operations.