Employing the Kings Indian Defense, Mariano smartly blocked the pawn storm of Anastasian, a former World Championship candidate who tried to break through the Filipino IMs kingside by giving a rook for a bishop.
But the clever Mariano countered on the queenside which Anastasian failed to dodge, forcing the fancied GM, rated 2587 to Marianos 2416, to resign on the 59th.
The win kept Mariano tied with super GM Liviu Dieter Nisepianu (2692) of Romania, Shkariyar Mamedyarov (2657) of Azerbaijan and Tamaz Gelashvili (2542) of Georgia.
Meanwhile, IM Barlo Nadera held GM Surya Ganguly of India, highly-rated at 2582, to a draw in 34 moves of an English opening for 2.5 points and a share of fifth with 21 others.
GM Bong Villamayor bounced back into contention by beating FIDE Master A.R. Saleh Jasim of the United Arab Emirates in only 28 moves of a Reti opening. Twenty eight players are tied at 2 points each.
Cristine Rose Mariano dropped her second game, this time against IM Chakravarth Deepan of India.
Mariano faces Mamenyarov, another World Championship Candidate, in the fourth round of the 9-round Swiss system event which drew 134 players from 39 countries, including 45 GMs.
Mariano and Nadera are gunning for their GM norms and have to score a prescribed number of points based on the strength of their opposition. A player needs to have GM norms in three tournaments covering at least 24 games.
Among the participants is 13-year old Magnus Carlsen of Norway who already has two GM norms and has scored 2.5 points in the Dubai Open.
"Should he make the cut, he could be the youngest GM in the world," World Chess Federation (FIDE) Rating Administrator Casto Abundo, the tournaments Chief Arbiter, said.
The Filipino International Arbiter secured the invitation for the Filipinos to participate in the Dubai Open and campaign for their GM titles. "There shall also be an Abu Dhabi Open soon," Abundo said of the capital of the United Arab Emirates" and the Abu Dhabi Chess Association and the Filipino Chess Players League of the UAE are ready to assist official representatives of the National Chess Federation of the Philippines," Abundo is also the NCFP Executive Director and FIDE Delegate.