"The boys played their heart out but eventually, the lack of experience cost us the match," he said.
"Some of the boys might have had a good game but I believe this is a team game where everyone needs to perform and they've had a great team effort tonight. We'll take it forward to the next game."
India lost 0-2 to Syria in their opening match at the Jassim Bin Hamad Stadium and they will have little time to recover as clash with hosts Qatar.
"They look very quick at times. They have an utmost quality I must say. It'll be a big challenge for us against them," he said.
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On being asked if Qatar's superlative performance in the AFC U23 Championship 2016 would impose a mental block to his boys, Constantine pointed out that "it's not the same team anymore."
"A lot of players from that batch might have graduated to the senior team. Their main advantage is that they're having the same coach throughout," he said.
Meanwhile, a decent number of supporters, clad in the Tricolour, were present in the stands to cheer for the youngsters.
"When you're playing at this stage, you want the stadium to be full. It keeps the adrenaline flowing amongst the players. Personally, I hope a good number of Indians will turn out in our support tomorrow.