THE sporting landscape in Sydney changed forever in a sea of red, black and light blue jerseys on Saturday night.

Rugby league used to own this city but soccer, football or whatever you want to call it is now a major player and competitor.

A crowd of more than 40,000 at Allianz Stadium on Saturday night proved the round-ball game has not just arrived but is bigger than rugby union and closing in on AFL and NRL.

The proof is at the turnstiles.

The average crowd for three NRL semi-finals at Allianz Stadium last month was 30,000.

BLOG WITH BUZZ ALL DAY

Then the A-League turn-up on Saturday night and fill the venue for a round three club game, even without the main drawcard Alessandro Del Piero.

media_camera The Wanderers celebrate winning the round three A-League match between Sydney FC and the Western Sydney Wanderers at Allianz Stadium on October 26, 2013 in Sydney, Australia. (Photo by Mark Nolan/Getty Images)

media_camera buzz

media_camera Fanatical... Sydney Wanders fans celebrate a goal on Saturday night. (Photo by Getty Images)

Who would have thought this could possibly happen - 40,388 fans at a Sydney soccer game.

The atmosphere was so different to a rugby league match, louder, more fanatical and more passionate.

The noise they make was louder than a rock concert, a chainsaw or a disco.

I know because I took a sound meter and spent the first 20 minutes of the game with the Wanderers supporters group the RBB and then 20 minutes with Sydney FC’s The Cove.

ARRIVING

I walk into the stadium with FFA boss David Gallop. It’s like a flashback to the old days, as though we’re arriving for an NRL blockbuster.

People are everywhere. Queues at the merchandise stalls, at the mobile TAB, the bar, food outlets, everywhere.

Gallop has to leave after 30 minutes for a prior commitment at the NSW Football Federation awards at Homebush.

He insists the grassroots are just as important as these A-League sell-outs.

Gallop is now involved in the grass roots himself. He has taken to playing soccer on Sunday mornings in a social competition in the eastern suburbs.

His weekend mornings in rugby league used to be about refereeing controversies, player misbehaviour, salary cap rorts or any other of the code’s regular dramas.

Not yesterday morning: "It’s (the crowd) further evidence that football is now a boom story in this city," Gallop said.

"To have 40,000 excited and engaged fans fill a stadium that is rarely totally full is just phenomenal."

media_camera Round ball passion...Wanderers fans

media_camera Wanderers fans celebrate during the round three A-League match between Sydney FC and the Western Sydney Wanderers at Allianz Stadium on October 26, 2013 in Sydney, Australia. (Photo by Mark Nolan/Getty Images)

THE NOISE

I took a professional quality sound meter, supplied by Acu-Vib Electronics.

Before the game it hovers around 90 DB and peaks at 94.5 as the players enter the stadium for the warm-up.

It reaches 99 DB when the Sydney FC players are announced on the big screen and 103 DB when they walk onto the pitch for kick-off.

I spend the first 20 minutes of the game with the RBB, wearing a Wanderers jersey for personal safety reasons, dodging beer that splashes out of plastic cups that become missiles when a goal is scored.

Sydney FC miss a free kick and the RBB goes off. The sound hits 111.5 DB. A flare goes off and the roar that follows records 110 DB.

Their first goal gets a 112 DB scream - and about a dozen flying plastic cups full of beer.

The song "Who do we sing for" is the noisiest moment of night – 117DB.

Still well short of the world record of 137 DB at an NFL game in Kansas City earlier this month but unbelievably loud, and almost painful on your ears.

I swap jerseys and move to the Paddington end of the Stadium to spend 20 minutes with the Cove.

In fairness, they didn’t have as much to cheer for and peaked at only 109 DB.

The groan when the little champion Shinji Ono scored measured at 105DB. Two-nil down and they were hurting.

media_camera Worship... Fans on Saturday night(Photo by Mark Nolan/Getty Images)

media_camera Wanderers supporters light a flare in the crowd during the round three A-League match between Sydney FC and the Western Sydney Wanderers at Allianz Stadium on October 26, 2013 in Sydney, Australia. (Photo by Mark Kolbe/Getty Images)

THE ATMOSPHERE

It’s like an NRL grand final or a State of Origin. The RBB and the Cove supporter groups are as much a part of the event as the players.

I find myself watching the cheer squads as much as the actual game.

Even Wanderers coach Tony Popovic is taken back by the enormity of the event and spectacle that the derby has now become.

"The atmosphere was unbelievable – as good as anything I’ve seen," he says.

"Better than last year and a credit to both sets of fans. Our fans are so special."

Frank Lowy and Gallop now believe they could just about fill ANZ Stadium if the return game is moved from Parramatta Stadium.

Sydney FC pocketed close to $500,000 from gate takings and the Wanderers would get double that if it was played at Homebush.

There are few incidents for the huge contingent of riot squad police at both ends of the ground.

A flare that exploded from the RBB end was the only major incident in an otherwise trouble-free night.

Most of the serious trouble makers were identified and banned last year.

media_camera Crazy... Wanders fans celebrate (Photo by Mark Nolan/Getty Images)

media_camera Shinji Ono of the Wanderers in action during the round three A-League match between Sydney FC and the Western Sydney Wanderers at Allianz Stadium on October 26, 2013 in Sydney, Australia. (Photo by Mark Nolan/Getty Images)

THE GAME

The standard of the A League is improving but this match was never really a contest.

The Wanderers led 2-nil after 25 minutes and it was basically game over.

Sydney FC has built a team around the superstar Del Piero – and when he doesn’t play – they lack the class and finishing touches to challenge the top teams.

I watch the second-half from ground level in the halfway line.

It mightn’t be Premier League quality but you admire the passion, the speed and the skill. Shinji Ono adds the touches of class and brilliance.

You wonder what the noise and atmosphere would have been like if Sydney FC had struck back with a goal or two. Or if Del Piero had played and scored.

Maybe a little bit closer to Kansas City and the NFL world record. Not that the A League hasn’t already achieved enough records of its own.

NOISE LEVELS

70 DB Vacuum Cleaner at 1m

80 DB Kerbside of a busy road

90 DB Diesel truck

95 DB Mark Bosnich’s laugh

100 DB Disco 1m from speaker

110 DB Chainsaw from 1m

115 DB Rock Concert

117 DB Wanderers v Sydney FC

137.5 DB NFL game world record

140 DB Jet aircraft from 50m