>> Day eight of the Rio Olympics, the spotlight on two of the game's biggest retiring names. American Michael Phelps clinching his 23rd gold in the water, with his team at the 4x100 medley. The most decorated Olympian of all time now says he's leaving the chase for good. He had previously said 2012 would be his last.
Meanwhile Jamaican sprinter Usain Bolt leading the field while qualifying for the 100 meter final, finishing the heat at what he called a sluggish 10.07 seconds. Bolt is aiming high, seeking to continue his gold streak in the 100, 200 and 4x100 relay, an unprecedented feat. He'll need to triumph over his arch rival, American Justin Gatlin, who qualified slightly ahead of Bolt by eight hundredths of a second.
Elsewhere on the track, Britain Mo Farah on his way to defend his two previous Olympic titles, winning the grueling 10,000 meter final, even after recovering from a fall at the start of his race. In tennis, a huge upset as Monica Puig overpowered German Angelique Kerber to take home Puerto Rico's first ever Olympic gold medal.
The 22-year-old twice beating Czech Wimbledon champion Petra Kvitova on her path to the podium. And in women's cycling, Britain beating the US in team pursuit retaining their title and smashing a world record at 10 minutes and 23 seconds. Back in the water, the United States won its 1,000th gold when its women's swim team won the 4x100 medley.
And look at this, a photo finish for single rower Mahe Drysdale of New Zealand edging out Croatia's Damir Martin for the gold. A dramatic day in Rio with more ahead.