Japan&rsquo;s Hideaki Yamauchi successfully defended his title at the IAU 100 km World Championship in Sveti Martin na Muri, Croatia, on Saturday (8) as his country dominated the top placings, while Nikolina Sustic took women&rsquo;s victory for the host nation.
Yamauchi clocked 6:28:05 in hot conditions to beat compatriot Takehiko Gyoba by almost five minutes. In third, South Africa&rsquo;s Bongmusa Mthembu (6:33:47) prevented a Japanese podium sweep, with Koji Hayasaka (6:36:05) next across the line.
On a course which was, unusually for these championships, undulating &ndash; its approximately 800m of elevation gain was pro rata the equivalent of the New York City Marathon &ndash; athletes covered 13 7.5km laps after an initial 2.5km out-and-back.
As Yamauchi slightly sat off the pace of the early leaders&rsquo; 4:00 kilometres (6:40 pace), USA&rsquo;s Geoff Burns, Gyoba and Britain&rsquo;s Lee Grantham pulled away on the second 7.5km lap of 29:23 with a lead of about 20 seconds by the end of it. Meanwhile, Yamauchi was content to maintain the pace 48 seconds back and behind the second group.
Although Burns and Gyoba stepped up the pace at the front with a 28:35 lap to go through 25km in 1:38:07 (6:32 pace), Yamauchi pulled back to just 26 seconds behind in the second group.
Despite the pace increasing with splits of 28:24 and 28:12, Burns and Gyoba&rsquo;s lead was cut back by several South Africans and Japanese as 40km was hit in 2:34:43 (6:26 pace).
At that point Yamauchi had drifted back 50 seconds off the lead but over the next lap, he put in a blistering 27:15 (equivalent to 6:03 for 100km) so that he, Gyoba and Mthembu were together at the front in 3:02:48 as Burns went back.
As Mthembu and Gyoba dropped fast 27:10 and 27:15 splits to go through 62.5km in 3:57:29, Yamauchi drifted 31 seconds off pace.
While Mthembu kept the tempo going to pass 70km in 4:24:40 (6:19 pace), Gyoba could not stick with it and was then 44 seconds behind in second, 1:56 ahead of Yamauchi.
The gaps grew at the front, but it was in the lap leading up to 85km that Mthembu up ahead and Gyoba started to suffer from the mid-race surge. Yamauchi was still able to split a 29-minute lap to go through in 5:27:03 in third, just over two minutes off the lead.
Yamauchi quickly clawed them in and went through 92.5km with a 61-second gap on Gyoba and Mthembu was struggling more than another minute behind.
A final split of 30:03 gave Yamauchi the victory &ndash; Japan&rsquo;s sixth in the past 10 editions. Mthembu rallied to pick up bronze &ndash; as did Burns, who picked up fifth in a sprint finish in 6:42:30.
Nao Kazami, who in Lake Saroma earlier this year beat Yamauchi to smash the world best with 6:09:14, was given the same time as Burns in sixth place.
However, it was sufficient to put Japan, with a cumulative time of 19:37:01, nearly an hour ahead of runners-up South Africa in the team standings. Germany, led by Alexander Dautel in 12th, was third. 
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Croatia's Nikolina Sustic (centre), winner of the IAU 100km World Championship</div>
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The women&rsquo;s race was very different with 41-year-old 2:44 marathon runner Radka Churanova setting a superfast pace at the front.
The Czech went through 10km in 42:35 and 25km in 1:45:34 to lead second-placed Nikolina Sustic at the latter stage by 1:42.
At 32.5km, passed in 2:17:22, she was on course for 7:02, which only three women have ever bettered. Saying afterwards that she felt comfortable up until about halfway, she then started to struggle with leg muscle cramps, which grew until at 80km she felt unable to even walk.
Sustic and Germany&rsquo;s Nele Alder-Baerens, who had been within two minutes of the Croatian at the end of every lap until then, passed her on the lap leading up to 47.5km. Meanwhile, Churanova maintained third up until past 70km.
Sustic, who ran a marathon PB of 2:42:44 for 34th place at the European Championships this year,&nbsp; went through 70km in 5:01:11 &ndash; on course for 7:10 &ndash; but with Nele Alder-Baerens just 69 seconds behind she could never relax. The margin was narrowed to just 17 seconds by 85km, but with a final lap of 35:19, Sustic came home in 7:20:34 to improve from silver last time out.
The national record raised her to 13th on the world all-time list and is the fastest in the world since 2015. Alder-Baerens, who has won gold at the Deaflympics and has a sight impairment, was timed at 7:22:41 for 17th on the all-time list.
Taking bronze in 7:39:07, Mai Fujisawa led three other Japanese women in succession across the line &ndash; Mikiko Ota, Aiko Kanematsu and Yuko Kusunose. With a cumulative time of 23:03:50, they took the team title by 53 minutes over South Africa with Croatia third.
Paul Halford for the IAAF
<h3>Leading results</h3>
Men 1 Hideaki Yamauchi (JPN) 6:28:05 2 Takehiko Gyoba (JPN) 6:32:51 3 Bongmusa Mthembu (RSA) 6:33:47 4 Koji Hayasaka (JPN) 6:36:05 5 Geoff Burns (USA) 6:42:30
Team 1 Japan 19:37:01 2 South Africa 20:33:49 3 Germany 21:02:12 4 USA 21:05:41 5 Spain 21:06:49
Women 1 Nikolina Sustic (CRO) 7:20:34 2 Nele Alder-Baerens (GER) 7:22:41 3 Mai Fujisawa (JPN) 7:39:07 4 Mikiko Ota (JPN) 7:39:45 5 Aiko Kanematsu (JPN) 7:44:58
Team 1 Japan 23:03:50 2 South Africa 23:56:44 3 Croatia 24:13:57 4 USA 24:32:02 5 Poland 24:46:54

Japan’s Hideaki Yamauchi successfully defended his title at the IAU 100 km World Championship in Sveti Martin na Muri, Croatia, on Saturday (8) as his country dominated the top placings, while Nikolina Sustic took women’s victory for the host nation.

Yamauchi and Sustic victorious at IAU 100 km World Championship