GUANGZHOU (NYTIMES) - A decade ago, this city in south-eastern China had a reputation as one of the country's grimmest, with smoggy skies, chronic traffic jams and streams so foul that they had to be paved over to contain the stench.

Today, Guangzhou represents one possible vision of China's future. While it still grapples with pollution and a wide wealth gap, the city has cleaned up many of its earlier problems, enjoys a modern, 192-station subway system and has a glittering cultural district, including an acclaimed opera hall. The cleaned-up bed of what was once one of its vilest streams is now lined with coffee shops and souvenir stores.

"The water quality here is far better than before," said Zhang Kun, a nearby noodle vendor. "Before, reeking water would pour out of storm drains whenever there was a heavy rain."

The city's progress cheers some advocates of reform as China prepares for its biggest leadership shake-up in five years. Among the candidates who may join the Communist Party's top body next week is Wang Yang, an official credited with fostering greener, more sustainable economic growth in Guangzhou and elsewhere in southeastern China when he was the top party official in Guangdong province.

But it is far less clear that Wang's voice would be heard over the voice of the party's supreme leader Xi Jinping, who has amassed power unseen in China since Mao Zedong and Deng Xiaoping.

If named to the Politburo Standing Committee, Wang would "be one of the seven," said Jean-Pierre Cabestan, a political scientist at Hong Kong Baptist University. "But Xi Jinping calls the shots, and he will be in charge."

By official figures, China's economy is doing just fine. On Thursday, China's National Bureau of Statistics announced that the economy grew 6.8 per cent in the third quarter from a year ago.

Economists widely believe those figures mask deeper problems. China's economy, the world's second largest, is burdened by debt from a borrowing-fueled binge of building rail lines, highways, bridges and apartment towers. It still relies heavily on dirty industries of the past, like steel and coal.

Xi has talked about economic reform, but debt ballooned under his watch. His policy measures have tended to focus on helping state-owned enterprises while retaining and even tightening Communist Party control of the entire economy, including private companies.

On Wednesday, speaking at the opening of the Communist Party's twice-per-decade congress, Xi said the party would "support state capital in becoming stronger, doing better and growing bigger."

Willy Lam, a specialist on the Beijing leadership at the Chinese University of Hong Kong, said: "It's difficult to imagine Xi Jinping moving toward a reformist position, because Xi Jinping is a pre-modern person. He is basically a man of the 1950s."

Xi's dominance has complicated the reading of tea leaves surrounding the selection of the Communist Party's new leaders. On economic matters, he has assumed much of the responsibility traditionally held by China's premier, who is currently Li Keqiang.

Still, when the party's congress closes next week, world economic leaders may glean some clues about China's direction depending on who is named to the Politburo Standing Committee, the seven-person group that makes its top decisions.

Should Wang be named to the committee, that could suggest a slightly greater emphasis over the next five years on economic reform, such as giving private enterprise more freedom or curbing dependence on state-directed lending.

The last party congress, five years ago, offered a hint of China's debt-fuelled approach under Xi.

Joining him then on the standing committee was Zhang Gaoli, who ran the large metropolis of Tianjin. Zhang was best known for leading a government effort to build a "New Manhattan" - a forest of immense office towers and apartment buildings far from downtown Tianjin, erected in the hope of creating a new financial center. The vast satellite city has begun attracting some residents in recent years but has yet to turn into a financial hub.

By contrast, Wang was the mayor of an obscure town in south-central China, Tongling, when he wrote a pro-reform essay in 1991 for a local newspaper. The essay - with lines like "History will never allow us to slumber on" - set off a lengthy discussion in Chinese newspapers, giving him a national reputation at the age of 36.

Wang moved up quickly after that, and by 2007 had become the Communist Party secretary running Guangdong province. Even before he arrived, the province was one of China's richest and most entrepreneurial, and more recently it has benefited from a boom in high-end technology manufacturing and the country's thriving internet scene.

Still, experts say Wang helped improve Guangdong. Wang's administration imposed stringent environmental rules that forced old and dirty industries to give way to new development. Wang oversaw the construction of the opera hall and other cultural attractions.

After 2012, as Xi pushed his government-centred economic strategies, Wang was named a vice-premier and largely disappeared inside Beijing's bureaucracy. There he was given responsibility for mitigating damage from earthquakes and floods and replanting forests.

Should Wang, now 62, finally join the party's standing committee and take a more senior position in government, he would have more influence but still would be carrying out an agenda drafted by Xi.

"Perhaps with Wang Yang," said Lam, of the Chinese University of Hong Kong, "they might be able to do a little more within the orders from Xi Jinping."