Olympic bronze medallist Saina Nehwal today became the first Indian to reach the finals of the World Badminton Championships, assuring herself of at least a silver medal here.

The World No.2 Indian notched up a 21-17 21-17 win over Indonesia's Lindaweni Fanetri, who was struggling with her right knee, in the semifinals of the women's singles.

In a repeat to this year's All England Championship final, second seed Saina will fight it out with defending champion and World No. 1 Carolina Marin of Spain in the summit clash tomorrow.

It would be India's fifth medal at the World Championship after P V Sindhu clinched the bronze twice in 2013 and 2014 and Jwala Gutta and Ashwini Ponnappa notched up a bronze in women's doubles at the 2011 edition.

Legendary shuttler Prakash Padukone was the first Indian to win a bronze at the 1983 edition.

It turned out to be a tight match as Saina and Lindaweni, who was playing with a strapping on her right knee, engaged in long rallies and gave each other a tough fight at the Gelora Bung Karno Stadium.

Lindaweni opened up a 6-2 lead early on in the first game as Saina tried to get a hang of the drift in the stadium. The Indonesian had to take some tips from the team doctor after feeling some pain in her knee at 7-6.

The Indonesian looked restricted in her movement as Saina clawed back at 9-9 and grabbed the lead next when Lindaweni hit wide. A service fault helped Lindaweni to level score at 10-10 but Saina went into the break with a 11-10 lead after winning a long rally.

After the interval, Saina increased the gap to 15-12 but the Indian committed a few unforced errors to allow Lindaweni draw parity at 15-15. A net fault and a wide shot by the Indonesian gave Saina a 18-16 lead.

Egged on by a vociferous crowd, the home girl kept fighting but a ferocious return took Saina to 19-17 lead. Lindaweni next found the net again as Saina gained three game points and the Indian pocketed it after her rival again hit wide.

Lindaweni struggled with her knee but she never gave up and matched Saina for strokes and went into the lead at 4-3. The Indonesian tried to vary the pace and came up with acute angled shots to trouble Saina.

Every time Saina took a lead, Lindaweni clawed back and turned the tables. The duo moved neck and neck from 6-6 to 10-10 before Saina moved into the break with a slender 11-10 lead.

After the breather, Saina opened up a 14-11 lead. But the Indian again committed a few unforced errors which helped Lindaweni to level par at 14-14. Saina once again surged ahead to 17-14 but Lindaweni showed steels of nerves to narrow it down to 16-17 and 17-18.

Saina eventually gained a three-match point advantage when Lindaweni hit long. Another wide shot from Lindaweni and Saina raised her arms in celebration.