Uruguay and Brazil complete the line-up at the Cathay Pacific/HSBC Hong Kong Sevens after finishing behind Argentina in the South American regional contest.
At last week's Sevens draw, organisers left two spots open in the 12-strong pre-qualification tournament for the finalists at the Consur Sevens (South American Confederation of Rugby) in Rio de Janeiro with hosts Brazil and Uruguay duly filling those berths.
They become the 27th and 28th teams at the Hong Kong Sevens from March 22 to 24. Argentina, a core team in the Sevens World Series, already had a berth.
Uruguay not only booked a spot in Hong Kong, but also qualified for the World Cup Sevens in Moscow in June. Argentina were automatic qualifiers.
"Going to the World Cup Sevens in Moscow is very important for us as a nation. And winning the Consur Sevens takes care of that and also gives us a place in Hong Kong. We are very happy," Uruguayan coach Luis Pedro Achard said.
Brazil's hopes of a World Cup berth were dashed by Uruguay who defeated them 17-5 in the round-robin competition.
But Brazil coach, former New Zealand sevens star Dallas Seymour, was still happy his side would be playing in Hong Kong for the second successive year.
"It came down to heart and passion. I am delighted for this team because they really deserve it," Seymour said.
Uruguay are drawn with Tonga, Tunisia, and Taiwan in the preliminary round of the pre-qualification tournament. Brazil are with Japan, Georgia and Jamaica. The other pool comprises Russia, Zimbabwe, Cook Islands and Mexico.
The top four teams from this regional tournament will join Asian champions Hong Kong in the final qualifying tournament at the London Sevens in May to decide the three core teams for next season.
Hong Kong will compete with the 15 core teams in the world series, at the Hong Kong Sevens tournament.