Rio Olympics 2016: Grandparents overwhelmed as Kyle Chambers wins swimming gold medal

The grandparents of swimming champion Kyle Chalmers were overwhelmed with emotion when the Australian young gun stormed home from the back of the field to win gold in the 100m freestyle final.

Malcolm and Julie Bagnell said they would have been proud of their 18-year-old grandson no matter what the result but could not hide their elation when he broke ahead of the pack, clocking 47.58, to claim gold in Rio on Thursday.

Mr Bagnell leapt to his feet and leant over to kiss his wife as she wept tears of joy in their lounge room in Port Lincoln, west of Adelaide.

Kyle Chalmers' win in the men's 100m freestyle final was emotional for his grandparents. Photo / AP

The 18-year-old schoolboy and Olympic debutant from Adelaide upstaged world No.1 and teammate Cameron McEvoy who finished seventh in 48.12.

The high school student is the first Australian to win the blue riband freestyle event at an Olympic Games since Michael Wenden in 1968.

Kyle Chalmers's grandparents were emotional after the gold medal-winning swim. Photo / Supplied

The pair travelled to Singapore last year to watch Chalmers swim in the FINA World Junior Championships, but could not join his parents Brett and Jodie Chalmers and his brother Jack in Rio as they cheered him on in the stands.

Chalmers said he left it all out in the pool and couldn't be happier to win his first Olympic gold.

Australia's Kyle Chalmers celebrates winning the gold in the men's 100m freestyle. Photo / AP

"It's awesome. I didn't have any more to give," he said. "But there's mixed emotions. It's hard winning and him (McEvoy) not swimming his best."

"It's definitely still sinking in I have actually won... I faded towards the end there especially when I got under the flags, I was worried I glided too long at that finish," Chalmers said.