The Manu 7s wore a black armband in their opening match against Canada to honour the victims of the measles epidemic which has taken more than 60 lives back in Samoa.
Sir Gordon Tietjens' side conceded two first half tries but responded in kind through Paul Scanlan and Tofatu Solia to go into the half-time break all square at 12-all.
The Samoans were reduced to six players when Joe Perez was yellow carded for a high tackle but dug in on defence to keep Canada scoreless in the second spell, with Elisapeta Alofipo sealing a 19-12 victory with the final try a minute from full-time.
Captain Tomasi Alosio said the team was "playing with a lot of emotion" after a difficult week.
"With one of the boys, Laaloi (Leilua) going back home to his family last weekend after his daughter getting measles and also finding out a few boys here in the team at the moment his daughter is struggling with measles as well so it's good to come out on top and Samoa this is for you," he said in a video posted on the Manu Samoa Sevens Facebook page.
"We dedicate this victory for the families of the victims of the measles - our hearts and prayers go out to you guys, the Manu Samoa Sevens here in Dubai are going to do it for you."
Meanwhile, Fiji survived a late scare to defeat Japan 24-17 in their opening match.
The defending World Series champions raced out to a 10-0 lead in the opening three minutes following tries from Vilimoni Botitu and Jerry Tuwai.
Isoa Tabu and Sevuloni Mocenacagi found the tryline early in the second spell to extend their lead to 24-5 but it wasn't quite the dream debut for their younger sibling, Kavekini Tabu, who was yellow carded in his first appearance on the World Series.
Japan scored two late tries, including one in stoppage time, to cut the deficit to seven points but it wasn't enough to deny Fiji a first-up win.
It wasn't such a happy start for the Fiji women's team, however, as they were thrashed 38-0 by Olympic champions Australia in their first pool match.
The Fijiana, who will face Spain and Ireland on Friday, are winless across their five World Series matches so far this season.
The Fiji men will round out pool play tonight against Argentina and France, with Samoa to face Wales and New Zealand.