Nehwal, currently ranked number two in the world, is virtually assured of the top spot when the updated rankings are announced next week, after Spain’s Carolina Marin, her nearest challenger and world number four, lost her semi-final match earlier in the day.
Marin lost a close, almost 90-minute match to Thailand’s Ratchanok Intanon 21-19, 21-23 and 22-20.
Indian Prime Minister Narendra Modi was among thousands of people on social media to congratulate Nehwal for her world ranking.
“The phenomenal accomplishments of @NSaina make us very proud. I congratulate her on being the world number 1,” Modi said on Twitter.
The 25-year-old will be the first woman shuttler from India to get the top world ranking.
On Saturday, Nehwal once again started the match with her trademark aggression and comfortably defeated her Japanese opponent 21-15, 21-11.
Nehwal, who has had a very good start to the year and even reached the final of the prestigious All England Championship earlier this month, is now the favourite to win the $250,000 Super Series tournament final on Sunday.
In the men’s tournament, China’s Chai Biao and Hong Wei defeated Russian duo Vladimir Ivanov and Ivan Sozonov 17-21, 21-18, 21-12 in a doubles contest that lasted a little over 50 minutes.
India’s K Srikanth, who defeated Japan’s unseeded Takuma Ueda to reach the semi-final, scored a comfortable win over China’s Xue Song 21-16 and 21-13 wrapping up the game within 42 minutes in front of a packed home crowd to reach the men’s final on Sunday.
Badminton’s world ranking takes into account a player’s 10 best performances over the past 52 weeks. Saina now dislodged China’s Li Xuerui from the top spot. Interestingly, the last time a non-Chinese achieved the World No. 1 status was in December, 2010 when Denmark’s Tine Baun had claimed the honour.