The top seed eased to straight game victories over Aaron Cheng (21-8, 21-12) and Alex Marritt (21-16, 21-11), and now faces youngster Alex Lane in the quarter-finals.
Hounslow-born Ouseph, who competed for Team GB at the London 2012, has won the last five Nationals titles but has suffered a dip in form since his early exit at the Olympics.
But he deemed himself satisfied with his opening day performances at the National Cycling Centre in Manchester.
“I think it was pretty good, I felt like I was a little bit quicker in the second game and quite comfortable but it was good for me to get a bit of a work out,” said the 28-year-old.
“You need to try and practise your shots and get a good length. It’s slightly difficult to control the shot a little bit sometimes but I think I used the two matches quite well and I feel comfortable in the hall.
“We are playing a lot of big tournaments and a lot of good players all of the time so it’s not often we get to play the later stages of these big tournaments so for us to keep winning matches is a good thing.
“If I can use this tournament to try and win some matches and take it into the international scene that is only a good thing.”
Next up, come & experience the world’s best players and London 2012 Olympians at the Yonex All England Open Badminton Championships. For more information, visit www.allenglandbadminton.com
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