Former Premier League referee Dermot Gallagher admits Leeds United were "very unlucky" to see a key decision go against them at West Ham.
Leeds saw a goal disallowed by a marginal offside call inside the opening 10 minutes of Monday night's clash at the London Stadium.
Tyler Roberts put the ball in the net but following a VAR review, Helder Costa was adjudged to have been fractionally offside in the build-up.
Gallagher felt some sympathy for Leeds, despite acknowledging that the correct decision was ultimately made based on the current interpretation of the rules.
"(It was) decided that Costa's knee was the furthest point forward that he could score a goal with," he told Sky Sports.
"So the (line) was drawn down from his knee to the back of the defender's foot, and it was felt he was just offside.
"I think this raises a number of issues. Firstly, as we say many, many times, I don't think people realised when they said VAR has to be a yes or no on offside, how tight the margins were.
"And I think the second thing here is that we've had this posed going forward next season they are going to experiment on offside, and I think that this would drive it even further forward for me, because that margin is so, so tight.
"People say to me (on Monday night), is that practical but what I would say is, it's the system. The system there is what all 20 teams operate to.
"And on this day, Leeds were very, very unlucky - but the system is there."
Leeds went on to lose the match 2-0 at West Ham, with goals from Jesse Lingard and Craig Dawson.
