Look: Linesman error wipes out City goal, shows need for video assistance

Manchester City was on the wrong end of an incredibly tight call late in the opening half of Sunday's FA Cup semi-final against Arsenal, as questions continue to be raised over the ability of referees - and, in this case, linesmen - to do their job without the much-needed assistance of video replay.

A Leroy Sane cross was adjudged to have crossed the line and gone out of play before curling back in and allowing Sergio Aguero to slam the ball just over the line - Raheem Sterling thumped it in for good measure, but the goal was wiped out by the linesman's raised flag.

Replays, however, suggest that the entire ball didn't cross the line, staying in play by the absolute slimmest of margins:

The ball seems to have stayed in play, and Pep Guardiola and Manchester City will likely be aggrieved after the contest when the incident is brought to their attention.

And yet, it's impossible not to think that such an incident is nearly impossible for anyone to see clearly in live time, as debate raged on even after multiple replays became available, while the linesman only got one shot to get the call right.

Video assistance is slowly being rolled out across world football, and incidents like this one - in matches where the stakes are enormous - continue to prove that technology is sorely needed in a sport that moves at tremendous speed, and where results can be decided by a matter of inches.