However the biggest cheer of the day was reserved for Rowan Varty who scored twice for the hosts.
The Welsh victory was revenge for a shock defeat to the same side last year and now sets Paul John's men up nicely for the second day's action where they will face Spain and group favourites South Africa.
John said: "The boys did what they had to do. We know from the past that Hong Kong can be tricky opponents so it was good to come through with a win.
"The win gives us confidence but we know we face a huge test tomorrow with South Africa in good form. However today has shown you can never rely on reputation to win games so we'll go into both games giving it 100 per cent."
The opening day saw several upsets with Russia beating Kenya 22-5 and Canada sneaking home 22-21 against Argentina, among the surprise results.