Both shuttler Kashyap, 25, and boxer Devendro, 20, displayed aggressive styles to demolish their respective opponents to storm into the pre-quarterfinals while archer Rahul Banerjee advanced to the round of 32.
Kashyap, from Hyderabad, lit up the morning by shocking his higher ranked rival Tien Minh Nguye of Vietnam, a quarter finalist at the last world championship, in straight games and progressed to the last 16 of men's singles.
Kashyap, ranked 21st in the world, outplayed his rival who is ranked 11 places above him, 21-9 21-14 in the second and final Group D match to clinch a berth in the knock-out stage by topping Group D, having beaten Tan Yuhan of Belgium in an earlier group match.
Kashyap next runs into Sri Lanka's Niluka Karunaratne who shocked eighth seed Kenichi Tago of Japan.
Manipuri lad Devendro made a sensational debut in the Olympics, storming into the pre-quarterfinals of men's light fly weight category (49kg) in just two minutes and 64 seconds at the ExCel Arena.
Devendro stopped his opponent Bayron Molina Figueroa of Hondurus with 36 seconds left in the opening round as the referee called a halt to the unequal contest.
The RSC verdict for Devendro helped him join teammates Vijender Singh and Jai Bhagwan in the pre-quarterfinals of the boxing competition.
Seasoned archer Rahul Banerjee entered the round of 32 of the men's individual event after comfortably beating Janstan Gantugs of Mongolia 6-0 at the Lord's Cricket Ground.
Banerjee provided some cheers in an otherwise dull day for the Indian archers as both Jayanta Talukdar and Chekrovolu Swuro crashed out in the opening round of the men's and women's individual events respectively.
Shuttle duo V Diju and Jwala Gutta and the three rowers - Swarn Singh Virk, Sandeep Kumar and Manjeet Singh - also put up a tame and listless display.
Talukdar and Swuro were beaten in the opening rounds of the individual events while the mixed doubles pair of Diju and Jwala also lost their second group match and got eliminated.
The country's trio of rowers also went out of medal reckoning and will to fight for minor places in men's single sculls and lightweight double sculls.
Virk failed to qualify for the semifinals of the single sculls as he came in fourth in the quarterfinals.
Sandeep and Manjeet finished sixth and last in the repechage 2 of the lightweight double sculls.
India's weightlifting campaign also ended on a dismal note with Katulu Ravi Kumar coming up with a below-par performance in the men's 69kg category.
Ravi Kumar, who had just recovered in time for the event after a bout of fever, lifted a below par 303kg -- 136kg in snatch and 167kg in clean and jerk -- to finish sixth in the 10-lifter Group B competition.
It was also curtains for Olympic debutant Garima Chaudhary who was eliminated from the judo competition after being defeated by an ippon (fall) by Yoshie Ueno of Japan in the opening round.
There was a setback in boxing too when the protest lodged by the Indians against the judging in the 81 kg bout between Sumit Sangwan and Brazilian Yamaguchi Falcao Florentino was thrown out by the jury.
'The protest has been rejected. The reasons were not given to us but in cases like these, it is extremely rare that a protest is accepted and the decision overturned,' national coach Gurbax Singh Sandhu told PTI.
Sumit lost 14-15 to Florentino in a closely-contested bout which left the Indian team and Sports Minister Ajay Maken enraged, prompting a quick protest.
Kashyap was the show stealer in morning action at the Wembley arena. The Indian shuttler was aggressive right from the word go and never let his rival settle down, and also set up points beautifully by opening the court before executing the winners with ease.
It was a match featuring long rallies and some attractive badminton and lasted 35 minutes.
Kashyap was delighted with the easy win but rued that his father could not be there to see him dominate the match.
"I expected to win but not that easily. Not that it was an easy game - we had some long rallies and when he gets into his rhythm he can be very dangerous." Kashyap said.
'My dad didn't get a UK visa in time. I don't know what's going on with the British Embassy. I feel really bad. I really wanted him to be here to see me play, especially in a match like this - to see me beat a player like this. I really hope that he'll get here tomorrow."
Talking about his rival Minh today, Kashyap said he was not an easy play to beat and that his strategy worked.
"Once he gets two or three points in a row he's very dangerous, so I really tried to keep it to two points only. If he gets five or six he can run away with the game.
"I trained really hard for this competition and I think I won because of my fitness levels," he said.
However, in mixed doubles, Jwala and Diju went down to the Korean pair of Jung Eun Ha and Young Dae Lee, who pulled off a comfortable 21-15 21-15 victory in a tussle that lasted 27 minutes.
The Indian duo, who had already suffered two losses earlier in the four-team pool, could not match the Koreans as they were far superior in all aspects of the game.
Elsewhere, shooter Abhinav Bindra, who has finished his engagement after shockingly failing to qualify for the 10 air rifle final yesterday and finishing a distant 16th, is the first Indian sportsperson to leave for home after finishing his assignment.
'There is no use my wasting time here. I finished my event so I am leaving. I have been away from home for long. So I am going back," said the Beijing Games gold medalist in an interaction with the mediapersons at the Games Village today.
"Obviously I am disappointed, but such is life," Bindra said before leaving for home. "Let us face it, you can't win all the time, but there is no shame in not getting what you want as long as you give your best to achieve that," he added.