The former South Africa head coach almost endured a nightmare start after Aderito Esteves scored a converted try to give Portugal a 7-5 lead deep into the second half.
However, with a minute left, star winger Collins Injera’s impressive turn of foot saw him motor into the corner to settle the contest.
Kenya dominated possession at the start but failed to convert it into meaningful opportunities until Oscar Ayodi burst free after his teammates won the ball from a Portugal scrum under the post just before the hooter for half time.
“It is good to be back and we wanted to get over that one. It is always better to win ugly than not at all. It was a good start, and now hopefully we can get better throughout the day.
“We are going to set our own milestones and own targets, it is going to take a while for the guys to learn the new philosophies, but as I said it’s building momentum and hopefully now we can move forward to the Cup quarters,” Treu said after game.
His charges face the sternest test in Group A when they take on HSBC World Series champions New Zealand later Friday.
The All Blacks got their Dubai charge off to a winning start by beating France 24-5.
Treu replaced Englishman Mike Friday at the helm of the side early November after the latter resigned in June after leading Kenya to fourth at the Rugby Sevens World Cup.