JAKARTA, Aug 15 — Lee Chong Wei of Malaysia cruised into his fourth straight men's singles final at the world championships today, but must overcome Chinese top seed Chen Long to win his elusive gold.

Lee, a three-time runner up at badminton's most prestigious event, advanced to yet another title match after swatting aside second seed Jan O. Jorgensen of Denmark 21-7, 21-19.

The former world number one is unseeded for the first time in years at this world championships, having just returned from an eight-month ban for doping.

But he's staged a ferocious comeback and looks dangerous as ever in Jakarta, dismissing four seeded opponents in his relentless march towards a maiden world crown.

But to end his gold-medal drought the Malaysian superstar must beat world number one Chen, who defeated him in last year's world championship final and has already won four titles this season.

"Last year and this year are very different," said 32-year-old Lee.

"This is my chance, and maybe my last opportunity."

Jorgensen, who will take home bronze after his impressive win over Chinese legend Lin Dan in the quarter finals, was caught completely off guard as Lee unleashed his full potential.

"You could say that I forgot how it is to play Lee Chong Wei," the Dane said.

"Nobody else in the world has that speed. I think he will win."

Chen smashed Kento Momota of Japan 21-9, 21-15 to advance to his second straight final, but acknowledged defending his world title this year would be no easy task.

China vs China mixed doubles final

Meanwhile world number one Carolina Marin, who almost didn't make the world championships due to injury, staged a gripping comeback against South Korea's Sung Ji-Hyun to book a second-straight finals appearance.

The top seed and defending champion screamed in triumph as she emerged victorious after a 90-minute battle over Sung 21-17, 15-21, 21-16.

Marin claimed the first game comfortably but lost her composure in the second, becoming increasingly frustrated as her unforced errors mounted and her lead slipped away.

She trailed Sung in the third game 13-8 before rallying, taking 10 unanswered points in a fiery comeback that left her Korean opponent spinning.

Marin was overjoyed at earning the chance to defend her world title, but conceded she let herself down mentally.

"Today I was nervous and sometimes I was angry with myself because I wasn't thinking about what I had to do, I was thinking about the score," the 22-year-old European champion told reporters.

"That made me angrier with myself."

Sung said she was struggling with stamina and cramps after enduring an 82-minute quarter-final marathon against Indian shuttler P.V. Sindhu.

Marin will face second seed Saina Nehwal after she brushed off local favourite Lindaweni Fanetri 21-17, 21-17 before a riotous home crowd.

The unseeded Indonesian, nursing a heavily taped knee, appeared a little heavy-footed at times and could not withstand the more agile Nehwal.

For a second year in a row it will be an all-Chinese affair in the finals of the mixed doubles.

Top-ranked pair Zhang Nang and Zhao Yunlei defeated resilient Indonesian duo Tontowi Ahmad and Liliyana Natsir, while fourth seeded Chinese pair Liu Cheng and Bao Yixin beat their second seeded compatriots Xu Chen and Ma Jin.

The finals line-up of the men's and women's doubles will be determined in semi-final clashes. — AFP