The former Lions skipper looked at the positives from the match while his Man City counterpart already has eyes on his next opponents
“Apart from the score, I am absolutely pleased with their performance," said Sellars.
"I think they [Singapore U15) are a young team. As you can see our boys are physically a lot stronger.
"Our boys trained every day and that might be the difference.
"Physical aspect we might be ahead of them but overall, their technical skills are good.”
When probed on his team's chances of being crowned champions, Sellars added: “I think the next game will be really tough and Ajax is a fantastic academy."
"I watched them play today and they are a good team and I guess this will be our toughest game so far in this tournament.”
His Singapore Under-15 counterpart, Nazri Nasir, took time to congratulate his opponents for their win.
“Congrats to Manchester City for the win and I think in today's match we can see how they outclassed us in many areas," said Nazri.
"My boys can’t match them physically and also fitness wise.
“But being three goals down at halftime, mentally, it’s not easy for the boys to come back into the game.
“I told them that they should be happy as they have a chance to play against such a team and it brings a valuable, and also a learning experience for them.”
Despite the heavy defeat and failure to progress to the semi-finals, Nazri did see some positive signs in his team.
“At least the boys tried to fight back and did not give up," he said.
"Especially in the last 15 minutes, we have players down and I have made five substitutions.
“I told them do not give up and not to concede anymore goals and they did it, and at the end of the day, there is nothing much we can ask for from the boys.”
The Cubs will take on Porto for the 5th/6th placing playoff on Sunday while Manchester City as group winners will take on Ajax Amsterdam who swept aside Porto 3-1 earlier in the day.