Ben: I swore I would stay up til 4am each and every night of the games. So far I have but tonight I am REALLY struggling! 

Ed Southgate: Some strong caffeinated dedication being shown over here by staying up until around 4 to watch the olympics 💪🏼🏊🏼🏅

Someone hasn't been following this live page for tips on how to stay awake and watch all of the action...

Michael Phelps is going for not just one gold medal, but two. He's in the USA's relay team...

For those of you suitably powered by caffeine and/or Olympics enthusiasm then Great Britain are in the 4x200m freestyle final at 03:38 BST.

GB's team of Duncan Scott, Stephen Milne, Robbie Renwick and Dan Wallace beat the United States to first in the heat by 0.43 seconds, with Russia third, and they will be joined by Germany, Japan, Australia, Belgium, and the Netherlands in the final.

Great Britain are the reigning world champions and are looking to win the contest for the first time since 1908.

Image source, Getty Images

I've said it already, but it really is a cracking bit of swimming we have in prospect tonight. 

Once the Phelps-Le Clos battle is out the way we have a rising star of British swimming going for a medal.

Siobhan-Marie O’Connor, who was the youngest member of the GB swimming squad at London 2012, shone on the pool at the 2014 Commonwealth Games, winning a gold, four silvers and a bronze.

That achievement was all the more impressive considering a year earlier she was diagnosed with ulcerative colitis, a condition that leaves a person's immune system significantly weakened and prone to becoming dangerously tired.

O'Connor breezed into tonight's final as the fastest qualifier with a British record time of 2:07.57. Standing in her way of gold, though, is Hungary’s Katinka Hosszu, who has won two golds so far in Rio.

Image source, Getty Images

We've had several shocks in the tennis so far in Rio, but it looks like Rafael Nadal is going to avoid being one of them. 

Nadal and Marc Lopez are up against Austria's pairing of Olivier Marach and Alexander Peya in the men's doubles. Watch that here.

All over in the women's football as Colombia earn a point - their first-ever at the Olympics - with a last-minute strike against the USA.

It doesn't change anything as far as the Americans are concerned - they progress to quarter-finals as Group G winners.

Ireland's David Joyce fought hard in the men's lightweight 60kg boxing, but it was no match for Azerbaijan's Albert Selimov who claimed victory winning all three rounds, the third by a unanimous decision. 

Drama! Kind of. Colombia have snatched an equaliser against USA right at the end, Catalina Usme pings in a beauty of a free-kick and it looks like this one will end in a draw...

In case you missed it, defending champion Serena Williams was knocked out by Ukraine's Elina Svitolina a little earlier, losing 4-6 3-6. 

An off-key Williams had unbelievably five double faults in one game.

Love it, Stephen. That's dedication.

"What an impressive lift"

Turkey's Ismayilov lifts an unbelievable 163kg - the biggest amount in his category - to put him in the lead.

Google also suggests 'winning breeds Westminster' in its search bar. 

Not heard that one before.

World and Olympic champions USA are closing in on victory against Colombia. They have fought back from 1-0 down to lead 2-1 with 15 minutes remaining.

USA are already through to the last eight, but a win in this game will ensure they finish the group stage unbeaten. Winning breeds confidence, as they say.

You can watch the closing stages of the game here.

Alistair Magowan
BBC Sport in Rio

GB windsurfer Nick Dempsey has won an appeal after being hit and knocked off his board by Lithuanian competitor Juozas Bernotas during the sixth race of the regatta.

Dempsey, who won silver at London 2012, leads the standings ahead of defending champion Dorian van Russelberghe of the Netherlands by a point, but will now increase his lead.

The incident led to the Brit finishing 14th, having won three of the first four races, but he will now be given an average score instead.

Woah. Come on people! This is no time to leave with some top quality swimming action coming up. A nap I'll allow.

Actually, for those of you following where it is the middle of the night, what's your strategy for keeping up to the very end of the day's action? Let us know via#bbcrio2016., external

We're halfway through this final, and it's pretty clear that three athletes are in a league of their own, at the snatch at least.

Kim Myong Hok of North Korea, China's Shi Zhiyong and Daniyar Ismayilov of Turkey only started lifting when their competitors had used up their three attempts at lower weights.

And it was Ismayilov who took the early lead, lifting 163kg.

Zhiyong is sitting second on 162kg followed by Hok, who managed 157kg.

Next up is the clean and jerk.