In another upset, Malaysian Abel Tam stopped giant-killer BR Raja's march by scores of 4 & 3 to set up a last four clash against 17-year-old Viraj.
Arshad Ali ousted Mohammad Sagor of Bangladesh 4 & 3 while Shubhankar Sharma showed Sri Lankan Vijitha Bandara the door also with a similar margin.
In the Viraj-Karan duel, it was Karan who called the first shots as he went 2-up after four holes.
However a lapse in concentration saw his lose the next hole. Meanwhile Viraj slowly grew in confidence and leveled on the 10th hole with a birdie.
In a see-saw battle, Karan still held the advantage of 1-up going into the final hole and committed a cardinal mistake and ended up with a bogey to lose the hole as the match then went into sudden death.
After both the players had shared honours on the first two holes, Viraj kept his nerves in control to shoot a par while his rival who had almost dominated the day's proceedings made a bogey to book his ticket back home.
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"We actually had lots of fun on the golf course as we have played a lot together. I knew I had to attack because match play is all about attacking golf but soon I realized I had overdone in the first nine. I then kept my cool and took it hole by hole, the 17-year-old Viraj said.
Arshad Ali will face Shubhankar Sharma the highest-ranked seed remaining in fray in the other semifinal.
Earlier during the day the 32nd ranked BR Raja continued his killing spree when he sent 17th seed Pratap Atwal home with a 2 & 1 victory in a pre-quarterfinal fixture. MORE