The 32-year-old from Kerala, who had recovered from a bout of chikungunya to compete in his maiden Olympics, squandered the opening game but got his acts together in time to notch up a 16-21 21-11 21-12 over the world number 70 Le in a hard-fought 62-minute battle.

A world championships and Asian Games bronze medallist, Prannoy will next face Lakshya Sen in an all-Indian pre-quarterfinal clash.

World No. 13 Prannoy looked a bit tired and a tad rusty as he couldn't control the proceedings early on.

Le dominated the rallies and in fact, held the lead at 8-7 after close initial duel. A precise shot at the corner gave the Vietnamese a crucial two-point lead.

Le used his jump smashes to trouble Prannoy, who couldn't play his game and fell 11-15 behind after the break. The Indian found the groove in time to make it 15-16 with an aggressive push at the back.

The Vietnamese moved up to an 18-15 lead after punishing a weak backhand from Prannoy and then unleashed another jump smash on his opponent's forehand to inch closer to the opening game.

Prannoy went long to hand four game points to Le, who shut the game when the Indian sprayed into the net.

After the change of sides, Prannoy opened up a 4-0 lead but Le slowly stepped up the pressure and narrowed it down to 7-8 when the Indian went to net.

Prannoy went into the break with an 11-7 cushion after producing a tight net shot.

The Indian looked calm and in control as he quickly wrapped up the game to take the match to the decider.

In the third game, Prannoy moved to 6-4 before the two played an aggressive flat exchange which ended with the Indian going wide. Le drew parity at 7-7 after an attacking return on the Indian's backhand.

Prannoy managed to grab an 11-8 lead after winning an aggressive flat exchange. The Indian stamped his class thereafter while Le couldn't get his attack going, as soon it was 18-11 in a jiffy.

The Indian quickly closed out the match when Le found the net again.

Prannoy had defeated Germany's Fabian Roth in the opening group match.