Yuki, ranked 195 in the world, took 76 minutes to stun 64th ranked Busta 6-4 6-3 in the opening round to set up a clash against third seed Fablo Fognini of Italy in the pre-quarterfinals.
Yuki, in all probability, will make the quarterfinals without taking the court as his next opponent, Fogini, who was partnering Indian ace Leander Pace, has pulled out from the men's doubles event due to a strain in his left leg.
But it has been learnt that Fogini would take a call on his participation in the singles event by tomorrow evening.
In a day of upsets, Russian qualifier Alexander Kudryavtsev sent packing eighth seed Roberto Bautista Agut of Spain in a long 107-minute tussle.
More From This Section
Kudryavtsev beat the 58th ranked Spaniard 6-4 3-6 6-3 and will now play Slovakian Aljaz Bedene in the next round.
Yuki, a rising star in Indian tennis, was at his attacking best today and concentrated on playing to his strength. He was was broken only once in the match.