Despite having healthy leads several times in the match, Saina could not hold her nerves and blew away the chance of an easy win.
The World No.6 lost the three-game match of one hour and eight minutes. The Japanese girl won 21-19, 22-24, 19-21 to better her career record to 2-3 against the Indian.
The Hyderabadi got off to a superb start in the year-ending $500,000 showpiece event. From 6-7 down, Saina notched six straight points to go 12-7 in the lead. Though the Japanese World No.13 closed down the gap to 19-20 in the end, Saina managed to clinch the significant point and pocket the first game.
Saina again got off to a dream start in the second game again, taking a 7-0 lead but Minatsu slowly found her footing and levelled at 11-all. The two exchanged serves almost after every point but from 19-all, Minatsu reached gamepoint. Saina saved three gamepoints but her opponent managed to clinch the fourth one to level the match.
Like in the first two games, the World No.6 took a sizeable 12-7 lead in the decider but the World No.13 once again closed the gap to level the match at 17-17. At 19-all it could have been anyone's game but Minatsu held her nerves to win the next two points and clinch the game and match.
Saina, a 2011 finalist here, needs to win her next two Group B matches to have any hopes of qualifying for the semi-finals. The Indian faces defending champion and World No.1 Li Xuerui of China Thursday.