Javier Gomez outsprinted Jonny Brownlee to be crowned world champion for a third time at a dramatic World Triathlon Grand Final in Hyde Park.
Brownlee finished second in the race and in the world series but his brother Alistair's hopes of a third world title were ended by an ankle injury.
The 25-year-old led the standings going into the race but was severely compromised on the 10 kilometre run, which is usually his strongest leg.
Alistair completed the race but he was knocked out of the overall top three, with Spain's Mario Mola taking the third spot on the podium.
It was a similar scenario to the women's race, with the standings very close between the top three, and the Brownlees and Gomez all emerged from the swim near the front of the pack.
A lead group of 13 formed on the bike, with the brothers shouting at the other riders to make sure the pace stayed high.
Alistair broke away on the bike in the previous race in Stockholm to take the pressure off the run, and the feeling was his ankle injury would force him to try to do the same.
His first real attempt came on the fifth lap, but Gomez responded immediately and he was pulled back.
The 25-year-old tried again as the lead group crossed the line to start the final lap, and this time he did manage to get a gap, but he did not make it stick.
As they came into transition, Alistair was visibly grimacing as soon as he began to run and it quickly became clear he would not be able to compete for the world title.
Jonny immediately surged to the front, closely tracked by Gomez, while Alistair was going at little more than jogging pace outside the top 10.
For a while the Olympic champion looked to have settled into a rhythm and he climbed back to fifth, but the pain clearly became too much and he dropped well back.
Jonny and Gomez were locked together, with both knowing only victory would be enough to give either of them the title.
Alistair signalled to Jonny as their paths crossed on the final lap, telling him to be clever if it went down to a sprint.
Gomez has often got the better of the Yorkshireman in similar scenarios, including in the Grand Final last year, although second was good enough for Jonny on that occasion.