Neither side had been able to make the breakthrough in the first period and Kasimov (pictured) decided to introduce Geynrikh at half-time having left him out of the starting line-up as the striker had been suffering from a fever.
It proved an inspired decision as Uzbekistan sewed up the points in the second period as Server Djeparov found the net just after the break before substitute Geynrikh scored a quick-fire double for the hosts.
Zaquan Abdul Radzak pulled a goal back for Malaysia but the damage had already been done as Uzbekistan closed in on a place in Qatar with their second win in two games in Group C.
“I asked the players to score a goal as soon as possible but they could not,” said Kasimov.
“I was disappointed with our performance in the first half as the players tried to play very quickly in the situations where they needed to control the ball.
“I decided to bring Geynrikh on because I realised that we needed to put on more pressure. I had kept him on the bench because he was sick yesterday and he did not participate in the training session. If we had scored goals in the first half I might not have sent Geynrikh onto the field.”
Malaysia have a quick chance to exact revenge, however, with the two sides to meet again on Wednesday in Bukit Jalil.
“As I said before the match, Malaysia are progressing and we must respect them,” added Kasimov.
“Our next match could be difficult because we will play in hot and warm conditions which will be totally different from that we had here today.”
Rajagobal echoed Kasimov’s comments that the introduction of Geynrikh proved decisive, conceding his players struggled to deal with the striker.
“I expected a tough game for us and we had prepared for it,” he said.
“I think we played good enough in the first half but Uzbekistan managed to put more pressure on us after half time and they scored an early goal in the second half.
“That was a crucial moment in the match. I asked my players to pay more attention to Geynrikh but they could not.
"Despite losing the match I’m proud of my team. They are young but they played well against a strong opponent in an away match.”