By Gabriel TanFollow @@gabetan13
The Warriors got the game at the Jalan Besar Stadium off to an awful start as they found themselves 2-0 down inside 12 minutes thanks to goals from Kunihiro Yamashita and Khairul Amri, and showed little desire to get back into the contest for most of the opening 45.
However, they were much better after the break and pulled one back in the 55th minute through a poacher's strike from new signing Sufian Anuar, but were nonetheless unable to find a second to force the draw and take the game to penalties.
Although he admitted his side's defending for both Tampines' goals left a little to be desired, Selvaraj was pleased with the way they came back in the second half.
"We lost concentration and went to sleep for a while and let them score two quick and easy goals," he said. "It's something we have got to work on.
"The second half was better, our tempo was higher and the boys started to believe even more that winning the game was possible. We penetrated more but we didn't create that many chances.
"We have got to work harder and come back stronger."
The ex-Singapore international did single marquee signing Kazuyuki Toda out for praise, although he was keen to caution his side not to be overreliant on the former Japan international.
"Different situations demand different types of play and not every ball should go to Toda," Selvaraj explained. "He could be a decoy.
"He's trying his best to make things good for the team but the rest of his team-mates must help him. This is very important especially at Warriors FC.
"He's performed as he has in training, he's a winner and doesn't want to be second in anything. I'm very happy with his performance and there's more to come from him."
On an evening where chances for both sides were few and far between, it was clear the Warriors sorely missed clinical Croatian striker Mislav Karoglan, who failed a late fitness test due to a back strain.
Still, Selvaraj believes both Sufian and Erwan Gunawan did well to fill his void and provide him with different attacking options for the upcoming Great Eastern-YEO's S.League season.
"We missed Mislav today [Friday]," he added. "The situation would have been better with him.
"Mislav has been very hungry of late but, while we missed him, it gave me an opportunity to look at the other strikers and I'm very happy with them, especially Sufian and Erwan. Both of them raised their levels today [Friday]."
The Warriors get their league campaign underway next Thursday when they visit Woodlands Wellington, who finished bottom last season.