Sindhu, who clinched two Super Series titles this season before winning a silver at the World Championship, will tomorrow face China's Chen Yufei, who saw off Thailand's Ratchanok Intanon 21-18 13-21 21-18 in another Group B match.
The 22-year-old Indian showed great anticipation and athleticism to completely dominate the proceedings even as Yamaguchi got buried under a heap of unforced errors in the last Group A women's singles match.
Before the match, Sindhu had a 4-2 head-to-head record against Yamaguchi, which included a win at the Hong Kong Super Series last month.
Sindhu made a rousing start to the match, zooming to a 5 -0 lead. An error at the net allowed Yamaguchi to break it before Sindhu wrested back the serve. The Japanese was effected by a series of unforced errors as she sent the shuttle flying wide and long.
Sindhu entered the opening break at 11-1 with a superb return and continued to rule the roost after the breather, reaching 15-4. Yamaguchi won points sporadically, exploiting the Indian's backhand a couple of times, but she failed to curb her unforced errors.
At 18-6, Sindhu committed a fault at the net but she followed that with a smash and gained 13 game points when her opponent went wide again.
Yamaguchi saved a couple of game points before Sindhu wrapped up the opening game with a delightful cross court drop.
The second game started on an equal footing with Sindhu and Yamaguchi splitting the initial four points after engaging in some fierce rallies. At 6-7, the duo engaged in a long rally before Yamaguchi sent it wide. A couple of unforced errors and Sindhu was leading 6-8.
The Japanese again narrowed it down to 8-9 before an accurate down-the-line smash and an error at the net by Yamaguchi helped Sindhu enter the lemon break with a three- point advantage.
The ordeal continued for Yamaguchi as she struggled to control the shuttle, allowing Sindhu to move to a 13-8 lead. A favourable video referral and a miscued shot by a stretched Sindhu gave a couple of points to the Japanese before Sindhu unleashed a roaring smash.
A low lift at the forecourt and an overhead return going to net further swelled Sindhu's lead. The Indian capitalised by a cross court drop, reaching 18-12.
A deceptive return and another miscued stroke by Yamaguchi handed Sindhu seven match points and she sealed it with a quick reflex near the net.
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