THE FOOTBALL world is in shock with the news that 1989 Brownlow medallist Paul Couch has died.

The former Geelong star was 51.

It is understood Couch suffered a heart attack while riding a bicycle.

Couch played in four Grand Finals in 259 games for the Cats between 1985 and 1997.

He won three best and fairest awards for Geelong and was a popular Brownlow medallist when he won the trophy aged just 25.

The Cats confirmed the news on Saturday afternoon, calling Couch "an icon" and "a friend to all who knew him".

"Paul was a critical player in returning the club to being a regular finals team and was a great big game performer," club CEO Brian Cook said.

"However it was as a fun-loving person, husband and father that Paul excelled. We pass on our deepest condolences to Paul's family and friends at this very sad time.

"Paul remained close to many at the club and to his teammates from the 1980s and 1990s. He will be deeply missed by all that knew him."

The AFL also offered its condolences in a statement.  

"Paul Couch was a bubbly, infectious figure with a ready smile who was a champion of our game," League CEO Gillon McLachlan said.

"His Geelong teams contested four Grand Finals across his career as a high-scoring and entertaining team to watch, with Couch pivotal to the regular forays deep into September.

"He was a consistent State of Origin representative and among the very best midfielders in the game his time, as evidenced by his stellar record.

"Off the field, he always presented with a large ready smile and was incredibly popular with all his peers. Our sincere condolences go out to his family from all the football community, which will greatly miss him."

Couch was named on the interchange bench in the Geelong Team of the Century, selected in 2001.

From Boggy Creek in Victoria's southwest district, he was a popular figure in the Geelong region, known for his knockabout approach to life.

Couch's son, Tom, played three games with Melbourne in 2012, and now plays with Collingwood's VFL side.

Geelong players wore black armbands for their clash with Essendon. Picture: AFL Media

Former Geelong president Frank Costa also paid tribute.

"It is a very, very sad occasion with Paul still a very young man. He was a very fine fellow and a bloke who always had a smile on his face. He's a guy that will be very, very sorely missed around the club," Costa told 3AW on Saturday.

"He was the boy from Boggy Creek and he came down as a quiet young country lad but he quickly gained confidence and became quite a personality around the club."

Costa described the well-liked clubman as "a happy person".

"If anyone wanted to have a word with him he'd stop and give you time. He's one of those convivial guys with a natural happy nature. There's not enough of them, and he's one that we're very, very sad to lose," Costa said.

The news emerged just hours before Geelong's NAB Challenge clash with Essendon in Shepparton, with both sides wearing black armbands in a tribute to Couch. 

Cats coach Chris Scott said the club had been rocked by the death of one of its former stars. 

"It's really terrible news. 'Couchy' was only 51, he's a great of our football club and is really close to a lot of people at our club," Scott said on Fox Footy. 

"It's a bit hard to comprehend, it's really raw at the moment. Our players will wear black armbands today and take a little bit of time to digest it as best we can and think of the best way to pay tribute to the great man."