Germany's Sebastian Brendel claimed an emotional gold medal in the men's canoe single 1000 metres, just a day after the death of his country's canoe coach Stefan Henze.
Henze died following a car crash near the Rio Olympic Park last week.
The 35-year-old 2004 Olympic silver medallist suffered head injuries when a taxi he was in with a team-mate crashed into a concrete barrier on Friday.
Brendel claimed gold however in a touching moment to retain his London 2012 Olympic crown.
The 28-year-old led for much of the race, but his Brazilian rival Isaquias Queiroz dos Santos stayed with the pace until the final 50m, when Brendel powered away to finish in 3min 56.926sec.
Moldova's Serghei Tarnovschi won bronze.
"From the beginning to the end, it was my best race ever," said Brendel.
"The Brazilian was very tough today, it was intense between me and him.
"I'm sure my family is celebrating and there will be a party when I get back home."
In a busy morning in canoe sprint, Gabriella Szabo and Danuta Kozak of Hungary held off a late charge from Germany's Franziska Weber and Tina Dietze to take gold in the women's kayak double 500m.
The Hungarians crossed the line in 1:43.687, just 0.051 seconds clear of the Germans who were the defending champions in the event from London 2012.
Poland's team of Karolina Naja and Beata Mikolajczyk took bronze.
The third race of the morning saw Lisa Carrington power her way to back-to-back Olympic gold medals and New Zealand's third at the Rio Games.
The defending Olympic K1 200m champion won the race in a time of 39.864sec, beating Poland's Marta Walczykiewicz and London silver medallist Inna Osipenko-Rodomska of Azerbaijan, who won silver and bronze respectively at Rodrigo de Freitas lagoon.
"It's amazing to finally make it here and do what I thought I could," said Carrington.
"The race is always very tight, we don't really know who's second or third.
"That's why I keep pushing."
In the fourth and final race of the morning English-born Spaniard Marcus Walz produced a remarkable finish to take the Olympic kayak 1,000m title.
Walz has an English father and a German mother, but grew up in Majorca, Spain.
The 21-year-old was fifth with 250 metres remaining before powering through to win with a time of 3:31.447.
The Czech Republic's Josef Dostal took silver in 3:32.145 and Russia's Roman Anoshkin won bronze in 3:33.363.