Day 4 at Rio: 13 talking points as Phelps takes his gold tally to 21

Heena Sidhu, competing in the 25m pistol event, failed to advance to the semifinals. She finished in 20th position with a total score of 576 out of a maximum 600.

Earlier, Heena had failed to qualify for the final of the women's 10m air pistol. In that event she finished 14th with 380 points. With this, Sidhu's Rio Olympics campaign has come to an end.

It's looking more and more likely that India will finish without a shooting medal at the Games, having won a silver in 2004, a gold in 2008 and a silver and a bronze at London 2012.

Dattu Bhokanal may have finished fourth in the quarterfinal round of the men's singles sculls to be out of the reckoning for a medal, but he has won our hearts. Bhokanal clocked 6:59.89 in the 2000m race, six seconds behind third-placed Natan Wegrzycki-Szymczyk of Poland. Bhokanal will now be fighting for the minor placings in semifinal C/D.

What should warm our hearts is that Bhokanal took up rowing only four years ago. Even more astonishingly, he was only able to afford an Olympic coach five months prior to the Games.

Atanu Das was definitely the star of the day for the Indians. He came into the Round of 64 on the back of a fifth place finish in the ranking round. That means he got a relatively easy opponent in Nepal's Jitbahadur Muktan, whom he blanked 6-0.

Onwards to his Round of 32, and a more tricky opponent in Cuba's Puentes Perez. Das started well and won the first two sets - 28-26, 29-26 - to go up 4-0. He then lost the next two sets - 26-27, 27-28 - by a point each. Thus, the two went into a fifth and final set, where Das hit two successive 10s to eliminate Puentes Perez and advance to the pre-quarterfinals, where he will take on South Korea's Lee Seung-yun on Friday, 12 August.

The Indian men's hockey team avoided another last minute disaster as it rallied from its agonising loss to Germany to defeat Argentina 2-1. The Indian team may have gone up 2-0, but once Argentina hit back, it was up against the wall.

Argentina got five penalty corners in the final fifteen minutes, but the Indian defence held on well to secure their second win of the group stage, and virtually secure their place in the quarterfinals.

India's boxing campaign got off to a promising start when Vikas Krishan Yadav won his bout against American Charles Conwell 3-0.

This is Krishan's second Olympics appearace, and he will now face �-nder Şipal of Turkey in the Round of 16 in the middleweight (75 kg) category.

Now that you're all up to speed with the Indians and what they've been up to on Day 4, here's everything else that has happened:

The defending Olympic champion may have not been at her best - owing to a shoulder injury - but a third round loss is still a big upset. She lost to 20th-ranked Ukraine Elina Svitolina, 6-4, 6-3. This caps off a disappointing Games for Serena, as she was knocked out alongside her sister Venus in the first round of the women's doubles event.

The pool was alive on Day 4 of the Games. Katie Ledecky and Katinka Hosszu were the stars of the day among the women swimmers.

Ledecky won her second gold medal of the Games when she outswam her competitors in the 200m freestyle with a timing of 1 minute 53.73 seconds. She was comfortably ahead of her Swedish rival Sarah Sjostrom, who finished in 1 minute 54.08 seconds. Ledecky is looking to be the first swimmer since Debbie Meyer in 1968 to win the 200m, 400m and 800m freestyles at the same Olympics.

Hosszu continued racking up the medals and has been the most talked about swimmer of these Games. On Tuesday, the 'Iron Lady' stamped her authority as she won her third gold medal of the Games. The Hungarian swimmer was impressive in her win in the 200m Individual Medley. She even created a new Olympic Record in the process with a timing of 2 minutes 6.58 seconds.

Michael Phelps is at it again. He's winning gold medals every time he enters the pool. The other day he won his 19th Olympic gold medal with a win in the 4x100m freestyle relay. On Day 4, he added number 20 and 21 with wins in the 200m butterfly and 4x200m freestyle relay.

After this blistering performance, people on Twitter began comparing him to countries' total Olympic medal haul. Take a look:

Japan came up with the upset of the Olympics. Well, that maybe a bit of a stretch, but still, it was huge. Japan stunned favourites New Zealand 14-12 in their Pool C Rugby Sevens opener.

A Katsuyuki Sakai conversion sealed the deal for the Japanese. Just as they did back in the 2015 Rugby World Cup, Japan have gone and done it again.

Australia were also upset by an impressive French team.

An official media bus travelling between one of the Games' four main competition zones and the main press hub was attacked by projectiles. No one was seriously injured in the attack.

"We don't know yet if the bus was shot, or it was a stone," organising committee spokesman Mario Andrada told The Associated Press. Three of the 12 journalists on the bus suffered minor injuries. Two windows were shattered.

Ever heard of a pool, especially one at the Olympics, turning green? No? Well, it happened during Day 4 of the Rio Games. Just take a look here:

Common folks like to carry their smartphones in their back pockets. But can you imagine a sportsperson doing that at the Olympics?

It happened during a fencing match at the Rio Olympics. The match on Sunday, 7 August, took place between France's Enzo Lefort and Germany's Peter Joppich. Photos and videos appear to show a black smartphone falling out of Lefort's left back pocket. Lefort was booed for this incident. He kicks the object around a few times before handing it off to someone off the mat.

And last, but not the least, a Dutch gymnast was sent home for not abiding by the rules. Yuri van Gelder was sent home in the middle of the Olympic Games for drinking.

Van Gelder had gone out partying on Saturday night, and when he returned on Sunday, he admitted to his indiscretion. This was a violation of Dutch Olympic team rules and as a result he had to pack his bags and go home.

This isn't his first transgression. Van Gelder was earlier suspended for one year in 2009 after testing positive for cocaine.