American Christian Taylor got back-to-back triple jump Olympic gold medals with a first-round effort while Croatia's Sandra Perkovic flirted with disaster before likewise repeating in the women's discus on a Tuesday which also saw Usain Bolt back in action.
Taylor hopped, stepped and jumped to 17.86 metres and later added two jumps of 17.77m which would have also been good enough for gold.
Perkovic fouled her first two throws as in the previous night's qualifying but in the face of elimination unleashed a throw of 69.21 metres, which was good enough for gold.
The Jamaican superstar Bolt meanwhile got a rousing reception from the at best half-full stadium as he won his 200m heat in a pedestrian 20.28 seconds, some 36 hours after his 100m gold.
The 200m are Bolt's pet event and part two of his Rio quest for a third straight sprint treble.
"I was nervous because the 200m is my favourite event. I didn't want to go out," he said. "I've recovered from the 100m. I'm tired now, but happy to be through."
Of his rivals, Canadian 100m third-place finisher Andre de Grasse had the fatest heats time of 20.09 seconds. The 400m bronze medallist LaShawn Merritt clocked 20.15 seconds, and fellow American 100m silver medallist Justin Gatlin conserved energy with 20.42 seconds.
The semi-finals are Wednesday and the final Thursday. Bolt is also in the Jamaican 4x100m relay which takes place Friday.
By the time Bolt ran under sunny skies Taylor had long bagged the triple jump gold in a dominant performance but fell short of the world record 18.29m from Jonathan Edwards in 1995 he had hoped to attack.
"I wanted the world record but it wasn't to be. I'll keep pushing for it. It's been there so long," said Taylor who was however more than delighted with another gold.
"I wanted it so much. It came together, the stars aligned," he said.
Fellow-American Will Claye took silver as in 2012 with 17.76m, and then proposed to girl-friend and American hurdler Queen Harrison.
"She said yes," the stadium announcer informed the fans.
China's Dong Bin grabbed bronze with 17.58m - as all medallists had their best result in the first round. Bing injured himself and had no further jump.
Perkovic got the maximum of only two legal throws from the nine in Rio, the third and last in qualifying and the gold medal-winning one as she celebrated while wildly draped in a Croatian flag.
Melina Robert-Michon delighted in silver with a French record of 66.73m and reigning world champion Caballero of Cuba took bronze with 65.34m.
In preliminary 1,500m action Taoufik Makhloufi of Algeria ran into the semi-finals along with Kenyan 2008 winner and three-time world champion Asbel Kiprop, the day after clinching 800m silver.
Former world champion Brianna Rollins led the 100m hurdles and Ethiopia's Almaz Ayana led the way into the 5,000m final by a mile, having already captured the 10,000m gold by smashing the world record.
The evening finals are the men's 110m hurdles and high jump, and the women's 1,500m set for the evening session.