- Marcus Fraser took a three-shot lead with the lowest Olympic round and Justin Rose scored the first Games hole in one when golf returned to the schedule after a 112-year absence.
- American swimming sensation Katie Ledecky's Rio domination continued when she broke the Olympic record in the 800-metre freestyle preliminaries.
- Defending champion Andy Murray needed a final-set fightback to book his place in the men's singles quarter-finals at the expense of Fabio Fognini, while Rafael Nadal also advanced.
- Fiji are assured of a first Olympic medal after beating Japan to set up a showdown with Great Britain in the men's rugby sevens final.
- Germany won the first two rowing gold medals of the Games before irrepressible New Zealand duo Hamish Bond and Eric Murray retained their men's pairs title.
QUOTES OF THE DAY
"It was either in or it was off the back edge. And the way the reaction was from the few people around the green we figured it had gone in. Although it would have been a great trick to play on me if it had gone 20 yards over the back." Rose reflects on his historic ace.
"I got to bed pretty late, or early. Like 3:15. And I'm not one that's very good at sleeping in so I was up by about 9, 9.30. I'm happy I get tonight off and get tomorrow off." Ledecky after breaking another record.
"I have got to complete all four rounds so I can say I am officially an Olympian. It is an amazing feeling. I want to smile all the time. The other night I wanted to cry because golf is in the Olympics and for the first time in my life I get to be the hero." - No doubting what it means to United States golfer Bubba Watson to play in the Olympics.
"If we put out a good race and we don't win we'll take it, we don't want to let the New Zealand rowing team down. We still have to execute, but the hard work is done in the four years leading up to this. It's the nature of being undefeated, because we can't exceed expectations - only match them." Bond after he and Murray won a remarkable 69th consecutive race.
Germany started the day with just a solitary gold medal, but rowing victories for the men and women's quadruple skulls teams and a shooting success for Barbara Engleder soon took their tally to four.
The United States top the medal table with 33 - 12 of those being gold - with China second on 25 (10 golds).
COMING UP: Biles to go solo for second gold, Phelps and Lochte showdown, track cycling in motion
The pressure will be on the incredible Simone Biles to win the women's individual all-around final after taking gold for the United States in the team showdown.
Michael Phelps and Ryan Lochte are set for what could be their final duel in the pool when they go in search of yet more glory in the 200 metre individual medley final.
The first track cycling medals will be up for grabs later on day six, while the men's team sprint the solitary final taking place on the opening night of competition.
Brazilian Adilson da Silva had the honour of hitting the opening tee shot in the first Olympic golf competition since 1904.
World number 288 Da Silva was in tears after he got proceedings started. He said: "It has been on my mind a lot. It was a privilege and a huge responsibility. It's hard not to get emotional."