Video reviews are already proving their worth in MLS

Slowly but surely, technology is making its mark on world soccer. Goal-line technology is already helping rule out goals in the Premier League, Germany's Bundesliga, France's Ligue 1 and Italy's Serie A and FIFA will soon embark on its plan to track players' fitness in real time.

But there's also something happening in some leagues around the world that could all but remove contentious decisions from the game: video assistant referees (VAR). This weekend, after a year of preliminary testing in official matches, video replays were unveiled at Major League Soccer matches, and it didn't take long for them to show their effectiveness.

FC Dallas became part of history as the first MLS team to have a goal ruled out by VAR. Dallas striker Maxi Urruti thought he had pulled a goal back when his side was 3-0 down to Philadelphia Union, but had it chalked off when a video review showed a foul on the Union goalkeeper.

That wasn't the only VAR decision this weekend. When the Portland Timbers met LA Galaxy on Sunday, goals came early. After just ten minutes, tied at 1-1, LA's Gyasi Zardes scored what appeared to be a messy but legitimate goal. A handful of Portland players, however, believed LA Galaxy had benefited from an unfair advantage. Footage of the goal was beamed to a pitch-side display, which revealed that Zardes had controlled the ball with his hand before bundling it into the net.

The event was described as a "key moment" in the match, but both coaches agreed it was a fair decision: "It was the correct reasoning, but it's a goal that we should have just headed in," said LA head coach Sigi Schmid. "In that moment, going down 2-1 vs. staying at 1-1, that was a key moment in the match," added Timbers manager Caleb Porter.

While both decisions were ultimately correct, VAR will likely stir up controversy. The video and official match referee are still the ultimate decision makers and must identify potential issues using the same tools that players, coaches and fans have access to.

Right now, the system can only be used to decide goal/no-goal decisions, penalty/no penalty decisions, direct red cards (not second yellow cards) and cases of mistaken identity. Despite its limitations, leagues and teams all over the world will be watching with a keen interest.