RIO DE JANEIRO (AP) — To win a taekwondo gold medal without doing much fighting is an accomplishment.

And that is largely how China's Zheng Shuyin took the women's heavyweight division title in a slow-paced final against Mexico's Maria Espinoza at the Rio de Janeiro Olympics on Saturday night.

Both fighters often appeared unwilling to spar and were penalized by the referee for passivity.

But Zheng's cautious, defensive approach ultimately allowed her to defeat Espinoza by a score of 5 to 0. Her considerable height advantage — she is six inches taller — also kept Espinoza at a distance while she used her longer legs to score quick points.

"I had this goal to become the Olympic champion but I knew it would not be easy," she said. Zheng said she hadn't yet decided how she would celebrate and would consult with her coach and the team.

The match was devoid of any of the more spectacular spinning techniques that taekwondo is known for; Espinoza attempted to score mainly by punching.

Zheng said she fights defensively because she worries that her opponents will be faster than her and have adopted strategies to counter her spinning kicks.

"Maybe I need to change my strategy to improve my score in the future," she said.

Espinoza previously won two Olympic medals: a gold at Beijing and bronze in London.

Zheng, 22, won a bronze at the Asian championships in April. Her Olympic gold medal is China's second in taekwondo at the Rio Games; Zheng's boyfriend Zhao Shuai took the men's 58-kilogram division on Wednesday.

The women's bronze medals were won by Britain's Bianca Walkden and Jackie Galloway of the U.S.

In the men's 80-kilogram plus division, Azerbaijan's Radik Isaev won the gold medal after defeating Niger's Abdoulrazak Issoufou in a cagey final where both fighters struggled with their timing and distance.

Isaev won by a score of 6-2.

Isaev, 26, is the current world champion and was the only fighter able to challenge Issoufou on the mat on Saturday. Although Issoufou stands at six feet nine inches tall, Isaev is just two inches shorter and was able to find ways to counter Issoufou's long reach and swinging head kicks.

Isaev was ultimately able to land two head shots on the hulking Issoufou that proved enough to secure victory.

Earlier in the day, Isaev defeated South Korea's Cha Dong-Min, a gold medalist at the Beijing Games.

The men's bronze medals were won by Brazil's Maicon Siqueira and South Korea's Cha Dong-Min.