Simon Biles, David Rudisha eye glory after Bolt heroics
Gymnastic sensation Simone Biles and Kenyan runner David Rudisha move into the spotlight temporarily vacated by Usain Bolt on Monday as Russia's lone track and field entrant Darya Klishina basked in getting clearance to take part in Rio.
US star Biles goes for a fourth gold on the beam having already captured the individual all-around and been part of the title-winning team event.
She could end the Games with six golds as she still has the floor and uneven bars to negotiate.
Before she entered the arena, Greece's Eleftherios Petrounias claimed gold on the rings while North Korean gymnast Ri Se-Gwang took the vault gold.
They were their countries' second golds of the Games.
On the track, Rudisha defends his 800m title.
The Kenyan coasted through the semi-finals, but pretenders to his crown include countrymen Alfred Kipketer and Ferguson Rotich.
Reigning women's 200m champion Allyson Felix is the star turn in the 400m and France's world record-holder Renaud Lavillenie defends his pole vault title.
Two gold medals in track and field were decided on Monday morning.
Kenyan-born Ruth Jebet won Bahrain's first ever Olympic gold when she claimed the women's 3000m steeplechase.
Poland's Anita Wlodarczyk smashed her own world record on her way to victory in the women's hammer throw with a monumental heave of 82.29m.
- Apology over Lochte -
Two big names will, however, be missing from the gold medal shake-up.
Former 200m gold medallist Veronica Campbell-Brown suffered a shock exit in the heats while reigning world champion Nicholas Bett of Kenya crashed out of the first round of the men's 400m hurdles.
Bolt, meanwhile, said he believes a new 200m world record is a possibility as he embarks on the next leg of his race for immortality.
The world's fastest man electrified Rio on Sunday by romping to a third consecutive gold in the 100m, the first leg of his bid for an amazing "triple triple."
Bolt, who is desperate to better his 2009 world best of 19.19sec, said a new record could be on the cards as he geared up for Tuesday's opening round of the 200m.
"I think if I can get a good night's rest after the semi-finals, it's possible," Bolt said.
Klishina, the Russian long-jumper who won a sports court order to get into the Olympics, has been left "confused" by the doping battle she is caught in, her lawyer said.
But Paul Greene said the Court of Arbitration for Sport (CAS) verdict in favour of the 25-year-old was "a victory for her and the individual rights of athletes who can stand up to a federation".
The International Association of Athletics Federations (IAAF) had approved Klishina as the only Russian entrant into the Rio Games but then excluded her in a shock move on Friday after getting new information about her doping samples.
Greene insisted that Klishina, who had been allowed into Rio because she is based in the United States and underwent regular international test, is "clean".
In dressage, Britain's Charlotte Dujardin won her third gold medal when she retained her individual gold.
The 31-year-old Dujardin also won silver in the team event last week and was a double gold medallist at the London Games four years ago.
Sharon van Rouwendaal of the Netherlands took the 10km open water gold in marathon swimming at the under-fire Copacabana beach venue.
Meanwhile, Rio Olympics organisers apologised to US swimmer Ryan Lochte after he was robbed at gunpoint.
Lochte and three team-mates were held up by criminals posing as police as they returned from a party.
Lochte had a gun put to his forehead in the robbery, when the swimmers' taxi was pulled over by criminals who forced them to lie on the ground and stole money and other items.
"We obviously regret that the violence has got so close to athletes," said spokesman Mario Andrada.
"We apologise to those involved and once again, we regret the fact that violence is an issue at these Games."