The greatest upset at Rio 2016, so far?

As we head into Day 12 of the Summer Games, Great Britain is second in the medals table — at least, the table ordered by gold-medals-won — and ahead of China.

There it is: United States, 26 gold medals; Great Britain, second with 16 gold medals; China third with 15 gold medals.

Wha-at?!?

That would be the China that won 51 golds at Beijing 2008 and 38 at London 2012.

This would be the Britain that won exactly one gold medal at Atlanta 1996, 36th in the standings.

As one social media user from China put it: “You kidding me?”

What is going on?

For one, the British made a commitment to improving their Olympic team following the 1996 embarrassment in Atlanta.

A significant percentage of British national lottery money goes to the GB Olympic Association — about 20 percent of it, at the moment — and that makes up about 75 percent of the money spent by the GB Olympic Association.

Since that one gold (and 15 total medals) of 1996, and the subsequent infusion of cash, here is how Team GB has fared:

Sydney 2000: 11 golds, 28 medals overall, 10th in the standings.

Athens 2004: Nine golds, 30 medals, 10th in the standings.

Beijing 2008: 19 golds, 47 medals, fourth in the standings.

London 2012: 29 golds, 65 medals, third in the standings (ahead of Russia).

And what we have now … the British team winning more gold than China.

The Guardian has done a piece revisiting the improvements to the British team, and “money” is right there at the top of key factors. It also suggests that the British have decided to view Olympics performances as a business idea — results for money spent — which began with a clustering of success in a few sports, but now seems to show British athletes being competitive nearly across the spectrum.

Meantime, China is struggling a bit. After the gold rush of the Beijing Games, the Chinese declined at London 2012 (from 51 gold to 38, from 100 total medals to 88) and seem destined for another decline in Rio.

Some in China are not happy about this, as can be seen in this story. Some Chinese officials are quoted saying that it isn’t really all that important to win tons of medals, and that it shows the growing maturity of Chinese society that not everyone feels compelled to have China right at the very top.

(Which is what nations say when they experience a drop in Olympics medals. “We have more important things to worry about,” et cetera.)

But back to the British.

They have a curious history of success in the Olympics.

They hosted the 1908 Games, in London, and dominated them, winning 56 golds and 146 medals overall, easily outstripping the United States, second with 23 and 47. (This is when the “sun never set on the British Empire”.)

But a process of attrition then set in, perhaps as the “gentleman amateurs” era began to get a bit ragged — but also because two world wars cost Britain a great treasure in money and manpower.

By Antwerp 1920, two years after the end of World War I, the British were down to 15 golds and 43 overall, third in the standings.

Going forward, note how often the British won about five golds and finished 10th or 11th in the medal standings. This persisted for decades.

Paris 1924: Nine golds, 34 overall, fourth in the standings.

Amsterdam 1928: Three golds, 20 overall, 11th in the standings.

Los Angeles 1932: Four golds, 16 overall, eighth in the standings.

Berlin 1936: Four golds, 14 overall, 10th in the standings.

London 1948: Three golds, 23 overall, 12th in the standings.

Helsinki 1952: One gold, 11 overall, 18th in the standings.

Melbourne 1956: Six golds, 24 overall, eighth in the standings.

Rome 1960: Two golds, 20 overall, 12th in the standings.

Tokyo 1964: Four golds, 18 overall, 10th in the standings.

Mexico City 1968: Five gold, 13 overall, 10th in the standings.

Munich 1972: Four golds, 18 overall, 12th in the standings.

Montreal 1976: Three golds, 13 overall, 13th in the standings.

Moscow 1980 (boycotted by the U.S.): Five golds, 21 overall, fifth in the standings.

Los Angeles 1984 (boycotted by the Soviets): Five golds, 37 overall, 10th in the standings.

Seoul 1988: Five golds, 24 overall, 12th in the standings.

Barcelona 1992: Five golds, 20 overall, 13th in the standings.

Atlanta … the bottoming out … one gold, 15 overall, 36th in the standings.

Since then, a steady climb: 11 and 28 (10th); nine and 30 (10th); 19 and 48 (fourth); 29 and 65 (third).

What is remarkable about the 16-and-41 performance so far in Rio is that the typical decline-after-hosting seems as if it will be muted, for the British.

They are unlikely to get close to 29 gold, but they may not be far off from the 65 overall medals, as they expand their victories into sports they have not been good at in a long time (rowing) or ever (gymnastics).

It is interesting to watch. Team GB seems to have become one of the most significant international markers for the country, behind perhaps only the monarchy, the Premier League and the pound sterling.

The British are no longer the 96-pound weaklings they were for more than eight decades and now are (as they would put it) “punching above their weight”.

An island nation of 60 million inhabitants is going head to head with China, a nation of 1.4 billion people, 20 times as many as Britain has. China also has the world’s second-biggest economy.

The British also are ahead of the Russians who, granted, are damaged by drug suspensions mostly focused on track and field and weightlifting. The Russians are down in fourth place, with 11 golds and 35 medals and seem likely to stay behind Britain.

China may and probably will catch Britain before the end of Rio 2016.

But that they are battling at all for second place, behind the U.S., shows how dramatically performances at the Olympic level can change.

Team GB is pushing, pushing, pushing and seems to have great institutional momentum. China has seemed to hit a lull.

The numbers prove it.