With the wind whipping through the small stadium and a drizzling rain falling almost the entire match, the U.S. played the first 20 minutes on shaky legs before warming up to the task.
Woznuk's goal on a sizzling half-volley into the roof of the net over the Danish goalkeeper Heidi Johansen in the 22nd minute was the USA's first shot on goal of the match, which was played in strong winds and drizzling rain.
The smallest player on the field at 5-foot-2, DiMartino found space to slide and smash a left-footed shot from just a few yards out after a corner kick was played into the box by Christie Rampone and headed by Natasha Kai off the arm of a Danish defender. The goal was the former UCLA star's first of her career and it came in her first career start for the USA.
"It's a special feeling to score a goal and, for Woznuk and DiMartino, who are fairly new to the team, it shows that on this team anyone can score," said U.S. coach Pia Sundhage. "Everyone is happy when anyone scores a goal, but especially the new players."
The match marked the debut of Shannon Boxx in the center of the U.S. defense, where she played performed extremely well next to Rampone.
The game was a rematch of the championship game the past two years.
"Even though it was raining, the field was pretty good," said Sundhage. "So we tried to play through the midfield and at times we managed to do that, especially after the first 20-25 minutes. Then every single player in the midfield got involved in every attack and I was very pleased with that."
The U.S. next faces Iceland on Friday in Ferreiras.
March 4 in Lagos, Portugal
USA 2 Denmark 0. Goals: Woznuk 22, DiMartino 35.
USA -- Solo, Mitts (Buehler, 46), Rampone, Boxx, Chalupny, O'Reilly (White, 78), Lloyd, Hucles, Woznuk (Rapinoe, 62), DiMartino (Tarpley, 46), Kai (Rodriguez, 62)
Denmark -- Johansen, Olsen, K.Pedersen (Marianne Pedersen, 67), Omtoft, Hansen, Knudsen, Sorensen (Christiansen, 72), Sand, Rasmussen, Pape (Nadim, 21), Merete Pedersen (Rydahl-Bukh, 67).
Yellow cards: USA -- Woznuk 32, Buehler 80, Rapinoe 85.
Referee: Jenny Palmqvist (Sweden).