In the super-long series, Troy Harold, who races in the 40-49 age group, is the overall men's leader on 392 points from four events.
Ed Hyde, a regular at the Xterra series since his first race in 2010, leads the 20-39 age group and is currently second overall male on 385 points.
Meanwhile, in the women's, Kristen Baker is the lead runner in the 20-39 age group. She is the overall super-long female leader with 353 points.
Baker will face a tough challenge from Canadian Lesley Turner Hall, who is second overall but has won every race she has entered after she missed the first race.
The enthusiastic Canuck, who is winning her 40-49 age group, is on 300 points and tipped to make a strong challenge for the women's overall title
The Xterra series is more than just about getting fit and having fun. The organiser, Total Sport, raises significant funds for its charity partners.
Last year, Total Sport donated over $100,000 to charities, which is no mean feat for a small company.
The Xterra series is benefiting Ronald McDonald House this year.
"We feel privileged and really pleased to be associated with Ronald McDonald House Auckland," says Aaron Carter of Total Sport.
"They are an amazing charity that provides a home and a support network for families with children requiring hospitalisation in Starship Hospital in Auckland."
Ronald McDonald House Auckland (RMHA) is proud to be Total Sport's charity of choice for the Xterra Run Series, which has been helping the House keep Kiwi families together and strong.
"The nature of the Xterra series, with its trail runs being suitable for all abilities, makes for the perfect family sporting event and it has been so nice to see families come together to participate," says Wayne Howett, the chief executive officer of RMHA.
"It is the ideal partnership for our charity, which supports families from all over New Zealand whose children need specialist medical treatment only available in Auckland, and we welcomed the opportunity to be involved.
"Each event has been joined by one of our courageous families who shared their experiences at RMHA with the Xterra participants.
"Imagine how difficult life would be if you had to be away from home for days, weeks or even months, whilst your child received specialist hospital care far from home."
"This is the reality for the 80 families, from all over New Zealand, staying at Ronald McDonald House Auckland tonight.
"Our House provides a safe haven where families can be together and face whatever the next few days may hold for them. Because families are stronger when they are together.
"We can't provide this essential service without the support of the Kiwi community and our partnership with Total Sport has played an integral role in helping New Zealand's families."
"The Xterra series has not only raised much needed funds for Ronald McDonald House Auckland, but has helped us in our House's endeavour to raise awareness, and we are thankful for their support," says Howett.