The Warriors went 67-15 during the regular season. The Blazers went 41-41.
Golden State is the favorite to win the championship.
"Anything can happen," Damian Lillard told USA Today Sports' Sam Amick. "It's the NBA. It's about playing right at the right time, playing well at the right time, and we believe that we can beat anybody. We're not going into the playoffs saying, 'All right, we got here, we did a great job, we fought back and let's just go in here and put up a fight.' We're going in here and we want to win.
"Ain't no moral victories and all that. We're coming to win. They're a great team. Nobody expects us to beat them. We have nothing to lose."
The Warriors won all four games against the Blazers during the regular season -- by 23, 45, 8 and 2.
It didn't look like Portland was going to get back to the playoffs this season, but the Blazers went 17-6 down the stretch to outlast the Nuggets for the 8 seed.
"We're competitive. We believe in ourselves," Lillard added. "It's going to be a tall task, but it's not like it's impossible. We're going in there to win it. We're going to go in there and put our best foot forward."
Last year, Golden State defeated Portland in five games in the Western Conference Semifinals.
Lillard averaged 31.8 points and 7.6 assists per game in the series and shot 43 percent from 3-point territory.
But he shot just 36 percent overall because he made just over 30 percent of his shots inside the arc.