A second half Malaysia rally, which included goals from ace striker Safee Sali and Abdul Hadi Yahaya, had brought the score back to 4-3 before Singapore veteran Aleksandar Duric grabbed his second and Singapore's fifth on a dramatic 2014 FIFA World Cup Qualifying Round Two night at Singapore Jalan Besar Stadium.
However, with the return leg to come at Kuala Lumpur's Bukit Jalil stadium on Thursday, Rajagobal remains optimistic that his side still has what it takes to progress to the next round.
"I am an optimistic man. If we can score two goals and we don't concede any to Singapore then we are there (in the next round), the former Malaysia international said.
"There are 90 minutes left and if we want to qualify we have to go and get the result.
"My players now have a few days before the game and we should be able to then give our best shot. I am confident and I think there will be a big difference at the Bukit Jalil."
Although upbeat about his side's chance of recovery, Rajagobal was nevertheless at a loss to explain why Malaysia, having taken a first minute lead, then found themselves 4-1 down at the interval.
"We got the best ever start and then the whole defence collapsed. We conceded goals which were both simple and sloppy," he said.
"I think my players went crazy and it looked as if they were nervous. They were lost and did not know what they were doing, it looked as if they were hypnotised. The first half was just crazy."
Malaysia's task was, however, not made any easier by the suspension handed to influential captain Safiq Rahim following his red card challenge on Hariss Harun. A fact Rajagobal was quick to recognise.
"He is a very influential player. When he got the red card my mind was already thinking about who could replace him (for the return leg)," he said.
"I now have to think of who will come into the team , but you have to be positive and have belief in the players you have."