Rio Olympics: Michael Phelps Eyes Golden Farewell, Usain Bolt Guns For 'Triple Treble'

Super Saturday at the Rio Olympics sees Michael Phelps aim for a golden last day in the pool and athletics' greats Usain Bolt and Mo Farah take to the track.

In tennis, giantkiller Monica Puig has a shot at landing Puerto Rico's first ever Olympic gold. Facing her in the women's singles final is German second seed Angelique Kerber.

The eighth day of the 2016 Games serves up 21 gold medals, that is one less than Phelps' phenomenal personal career haul.

The 31-year-old superstar goes for a 23rd and last gold in the 4x100m medley relay and looks a certainty.

The US team are undefeated on the Olympic stage in the medley relay, with Australia the only other team to have captured Games gold -- in 1980 when the Americans boycotted Moscow.

Over at the Olympic stadium day two in athletics sees one of sport's biggest draws begin his 'Treble Treble' quest.

Bolt, like Phelps also in his last Olympics, is gunning for 100m, 200m and 4x100m relay gold after sweeping the titles in 2008 and 2012.

The Jamaican star embarks on the first leg of the opening heats of the 100m before the final on Sunday.

Bolt is not the only one chasing three-peat immortality, as his compatriot Shelly-Ann Fraser-Pryce attempts to complete an unprecedented hat-trick of Olympic gold in the woman's 100m.

The 29-year-old however could face a stiff challenge from compatriot Elaine Thompson, the fastest woman in the world this year with a time of 10.70 seconds.

It will take around 26 minutes more to watch the men's 10,000m where all eyes will be on British hot favourite Farah as he defends his London 2012 title.

The poster-girl for the last Olympics, Jessica Ennis-Hill, is defending her heptathlon crown, and is leading after Friday's opening legs ahead of Saturday's long jump, javelin and 800m.

Britain's Greg Rutherford scraped into the finals to defend his 2012 long jump crown.

At the tennis, Puig is hoping she can continue her giant-slaying run for her date with Australian Open champion Kleber.

In the men's semi-finals, Rafael Nadal faces Argentine Juan Martin del Potro and defending champion Andy Murray plays Japan's Kei Nishikori.

Australian Marcus Fraser leads new Olympic sport golf going into the third round by one shot from Belgium's Thomas Pieters.

In football, Brazil superstar Neymar renews his bruising rivalry with Colombia in the quarter-finals while Germany face Portugal in a clash of world and European champions.

Neymar suffered a cracked vertebrae when he played the Colombians at the World Cup two years ago.

After two goalless draws the 2016 Olympic hosts finally got their campaign up and running with a 4-0 win over Denmark in midweek.

Relief was the buzzword in the squad as they seek to restore pride with the 7-1 thrashing by Germany at their own World Cup still hurting.

The velodrome dishes up two gold medals in the women's team pursuit and keirin.

There are also finals being fought out in rowing, fencing, weightlifting, shooting and trampoline.