Gemmell bided his time on the run, staying on the shoulder of Jarrod Shoemaker (USA) and Laurent Vidal (FRA) before comfortably running clear to win by 9 seconds.
Warriner ended her season in style with a commanding victory that earned her the world number one ranking for the year.
According to TVNZ:
Gemmell's victory followed quickly on the heels of Sam Warriner's win and Andrea Hewitt's 6th place in the women's race, ensuring the Kiwis ended the World Cup season with a reminder as to which country is number one for triathlon talent and depth in 2008.
The win will be bittersweet for Gemmell after the disappointment of the Olympic Games but shows the tremendous heart that powers this Palmerston North athlete and signals his intentions for 2009 and beyond.
Temperatures reached the early 30's in Huatulco, making for a high attrition rate lower down the field.
The field exited the non wetsuit swim in almost one large group before a number of attacks came on the bike.
Gemmell was amongst those attacking and late in the bike had made a move, clearing out from the chasing pack by 10 seconds at one stage. But this proved unsuccessful, as the group once again came together heading into transition two.