The brother-in-law and teammate of Robert Carpenter has described the moment he saw the amateur goalkeeper collapse between the posts during a soccer match in Brisbane on Saturday.

Mr Carpenter, 25, suffered a heart attack just after 1.30pm at the Eagles Sports Complex in Mansfield, in Brisbane's south.

He played for Blackstone United Dragons Soccer Club along with his brother-in-law, Ashleigh Fryer, who saw the tragedy and said there were no warning signs.

Mr Fryer said he ran over to Mr Carpenter when he saw he had collapsed and watched as paramedics tried to save him. Mr Carpenter later died at Princess Alexandra Hospital.

"Robbie always told me before every game how he felt and there was nothing out of the ordinary on Saturday," Mr Fryer said.

"He was the most down-to-earth bloke you could ever meet and always there for everyone. He was gentle, honest and overall a top bloke.

"He was a great mate to many, he was a clown and would light up any dull moment. I'm just shocked and gutted.

"He wasn't just an uncle, son or mate - he was so much more."

Mr Fryer said his brother-in-law loved all kinds of sports. He had started playing soccer again after playing throughout his childhood and supporting English Premier League club Manchester United, he was a rugby league fan and also used to watch the Brisbane International tennis tournament with his mother.

It was only the second game of the season when Mr Carpenter died and the team vowed to play on in memory of their fallen teammate.

"The rest of the season is going to be a tribute to Robbie, he would want us to keep going," Mr Fryer said.

"He would say 'carry on boys, don't stop for me'."

Mr Fryer said the support friends and family had received from the broader soccer community was comforting.

Mr Carpenter's mother, Hannah, paid tribute to her son, who she described as "the most perfect person".

"He was funny, loving, easy-going and lived life to the max. Not a bad word can be said about him by anyone," she said.

"You are going to be greatly missed .... (by) all your family and friends from all over the world."

Mr Carpenter's sister Melanie, who is Mr Fryer's fiancee, posted on Facebook that her brother died doing what he loved.

"This will be a massive shock to many, and please help and guide us through this trying time," she said.

"May you rest gently and quietly. I love you my big brother."

Team chairman Jeremy Bruce posted on Facebook the club's thoughts and prayers were with Mr Carpenter's family, friends and teammates.

"We ask that you continue to uphold the family in your prayers as they come to terms with the loss of a son, brother and mate," Mr Bruce said.

Blackstone United Dragons are part of the Queensland Christian Soccer Association, which encourages games to be played on days other than Sunday.

With AAP