The world number two Indian squandered a one-game lead to go down 21-17 13-21 13-21 in little less than hour against unseeded Fanetri at the Singapore Indoor Stadium.
It was a neck-and-neck battle till the first 10 points of the opening game before Saina took a three point lead at 14-11.
The Indian increased her lead to 17-13 before Fanetri clawed her way back to reduce the margin to just one point at 18-17. But Saina regained her composure and pocketed three straight points to close the game in her favour.
Riding on her smashes and delicate net play, Fanetri increased her lead to 19-10 before sealing the game in her favour to level the scores.
The win in the second game gave immense confidence to Fanetri of registering an upset victory over her higher-ranked opponent as she carried on her good form to open up a 12-3 lead over Saina with clear winners.
The Indonesian did not give any chance to Saina to make a comeback as she increased her lead to 19-9 before giving the knockout punch to the second seeded Indian.
