Old stager Stefan Pereira tapped in on the half-hour mark. And Southern thought the job was done when Matthew Chan Ching-him turned into his own net 11 minutes after half-time.

But Tang’s goal ushered in a period of home pressure, with Southern suddenly ragged, only for the persistent Mahama Awal to put the game to bed with seven minutes left.

“We expected three points and finally got them and I was so pleased about that,” Yeung told the Post.

“The way we played after going 3-0 in front was not my expectation – maybe our concentration was going down, or we were losing energy, or had a physical problem. I need to find out what happened. It was the most dangerous moment for us.

“This match shows we have to really concentrate in every game. I was not surprised by Junior, he is a quality player, I am happy he scored and played well in defence.”

Young keeper Ng will train with the Hong Kong Under-23 team this week as part of preparations for next month’s Asian Games. He flew to his left to tip Panupong Wongpila’s swerving drive onto the post when the game was scoreless.

And when the hosts tried to muster a fightback from two goals down after 34 minutes, the 21-year-old brilliantly flicked Ismael Dunga’s point-blank header onto the bar.

“They were magic moments and he saved our team,” Yeung added. “He is a potential Hong Kong player, there are not many good goalkeepers in Hong Kong but he is one of them.”

Sham Shui Po head coach Lawrence Tang Kwun-yin insisted his game plan “needs improvement” after Southern repeatedly exposed the hosts when breaking forwards with speed.

The opening goal came from a dead ball, however. Chen collected a short corner to tee-up Junior for the finish.

Pereira, who netted 13 league goals last term, pounced when Shu Sasaki recovered possession on the right to square for the Brazilian in front of goal. And the wheels were coming off for Sham Shui Po when defender Chan steered substitute Raphael Merkies’ skimming cross past his own goalkeeper, Oleksii Shliakotin.

Tang, introduced on the left of midfield for the second half, squeezed a shot inside Ng’s left post, before the keeper saved twice in quick succession from Wongpila. But Awal, the Hong Kong international forward, extinguished home hopes with a rising drive beyond Shliakotin.

“My strategy needs improvement, it wasn’t good and the details can be better,” Tang said.

“We couldn’t stop the counter-attack, they were fast and we couldn’t condense the space, so they could play easily, especially on the flanks.

“I told the players to condense the middle and they followed my instructions, but the switching needs more details, who is going and who is dropping and who is the first defender.”

Tang injected more purpose into Sham Shui Po’s football. But his boss was sparing in his praise for the 24-year-old.

“I brought him on because I wanted to improve both attacking and defending on the flanks, there was too much space for Southern to attack,” Tang added.

“I was 50-50 on his performance – in defending, his movement and positioning need to improve.”

Sham Shui Po’s new defender Nii Noye Narh, meanwhile, was absent with a muscle tear and is expected to miss three weeks.