Ghosal, bidding for his eleventh crown, and Mangaonkar scored straight-game victories over Ranjit Singh and Abhishek Pradhan respectively to enter the quarterfinals.
Former champion Harinder Pal Sandhu, seeded 3/4, was taken the distance and had go come back from 1-2 before showing the exit door to qualifier Gaurav Nandrajog in a tough battle.
A gallant Nandrajog, runner-up in the 2006 nationals, came close to fashioning the competition's first significant upset before Sandhu rallied to a hard-fought 11-3 11-6 8-11 4-11 11-1 win to set up his next clash with Ravi Dixit.
In the women's man draw, top two seeds - defending champion Joshna Chinappa and no. 2 Dipika Pallikal, playing her first nationals after 2011, also reached the second round with straight-game wins.
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Results (Seedings in bracket):
Men (1st round): Saurav Ghosal [1] bt Ranjit Singh 11-3 11-5 11-8; Vijay Kumar [5/8] bt Veer Chotrani 11-5 11-2 11-7; Vikram Malhotra [3/4] bt Sandeep Jangra 11-7 11-3 11-9; Harinder Pal Singh Sandhu [3/4] bt Gaurav Nandrajog 11-3 11-6 8-11 4-11 11-1; Ravi Dixit [5/8] bt Krish Kapur 12-10 11-6 11-8; Velavan Senthilkumar [5/8] bt Aryaman Adik 11-6 11-8 9-11 11-5; Mahesh Mangaonkar [2] bt Abhishek Pradhan 11-3 11-9 11-5.