The 21-year-old Rehenesh denied Delhi captain Alessandro del Piero in what could have been his first goal of the ISL in the 39th minute as he he dived full length to his right after the Italian legend's free kick had beaten the defensive wall.
The Kerala goalkeeper then made diving saves to deny Delhi striker Hans Mulder twice -- in the 87th and 90th minutes -- much to the agony of the home supporters.
The Dynamos are unbeaten in the league with three draws and a win.
NorthEast were without marquee player Joan Capdevila and Koke due to injuries but despite their absence, the match was evenly contested with the biggest crowd turning up at the Jawaharlal Nehru Stadium.
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The visiting team had their share of supporters among the 20,000-odd crowd with a large number of Delhi-based youngsters from the eight states of that region turning up.
The 39-year-old Del Piero also tried his luck from his trademark free-kick in the 39th minute but was denied by a beautiful work by the NorthEast keeper, who dived to his right to pluck the ball.
Del Piero was later substituted in the 57th minute by Brazilian Gustavo Dos Santos.
In between, NorthEast striker James Keene's strike from inside the box off a pass by Durga Boro was saved brilliantly by Delhi goalkeeper Kristof Van Hout's long legs.