By Ian Ransom

HANGZHOU, China (Reuters) -North Korea's Ri Song Gum set a weightlifting world record at the Asian Games where Chinese tennis trailblazer Zhang Zhizhen claimed his nation's first men's singles gold medal in nearly 30 years on Saturday.

The 25-year-old Ri jumped for joy after hoisting a combined 216kg to win the gold medal in the women's 49-kg category, re-writing the record books only a few weeks after China's runnerup Jiang Huihua lifted 215kg at the world championships in Saudi Arabia.

Ri cried on the podium and saluted as her national anthem played, having won North Korea's fourth gold at the nation's first appearance at a major multi-sport event in five years.

"During the COVID period I did a lot of hard training and that’s why today I achieved this great result and broke the world record," said Ri.

"When I see my national flag flying I feel very excited to bring this good news to my people."

There was more joy for North Korea in the women's soccer as a late three-goal burst secured a 4-1 win over South Korea in the quarter-finals at the Wenzhou Sport Stadium, with midfielder Ri Hak scoring a double.

Without a FIFA ranking after not playing international football for years due to COVID-19, the North Koreans have come back with a bang in Hangzhou.

In the tennis, Zhang rode a wave of crowd support to beat Japan's Yosuke Watanuki 6-4 7-6(7) in the men's singles final, roaring back from 4-1 down in the first set after a nervous start at the Olympic Sports Centre.

The first Chinese man to break into the top 100 in world rankings, Zhang wrapped up the match after Japanese number two Watanuki blew a set point in the tiebreaker with a double-fault.

Zhang tossed his racket away in celebration as home fans erupted and walked around the court draped in the red flag of China.

It was the hosts' first gold medal in the men's event since Pan Bing won back-to-back titles in 1990-94.

"It's been a very, very tough week, not just this match, but very tough for the whole week actually, from the first match onwards," said Zhang.

"But I'm super happy that from the beginning of the first match, step by step, I've played better and better tennis."

China's Zheng Qinwen won the women's singles title on Friday, overpowering compatriot Zhu Lin 6-2 6-4.

An outlier among the traditional east Asian powers of table tennis, Iran savoured one of its finest days in the sport when brothers Nima Alamian and Noshad Alamiyan thrashed Japan 3-0 in the quarter-finals of the men's doubles.

The Iranians already took a bronze in the men's team event.

"I can't even believe it myself now. It's like I'm dreaming. It's amazing," said Alamian, whose father and uncle also played on the national team.

"My father is super happy," added his brother, Noshad. "He cannot believe this either."

It was business as usual for China on day one of the diving, however, with Olympic champion Quan Hongchan and Chen Yuxi obliterating their rivals to win the women's synchronised 10-metre platform gold with a total score of 375.30 points, more than 80 better than runners-up Japan. China also won the men's double synchronised 3-metre springboard convincingly, ahead of South Korea.

Japan's Yuko Takahashi became the first athlete to win the women's triathlon back-to-back, five years on from taking gold at Jakarta.

Takahashi held off China's runnerup Lin Xinyu and bronze medallist Yang Yifan in the gruelling course in Chun'an county, a day after compatriot Kenji Nener took the men's gold for Japan.

"I did a lot of test runs before the competition, but it was so difficult because of the steep hills," said the exhausted 32-year-old.

(Reporting by Ian Ransom; Editing by Michael Perry and Hugh Lawson)