The Americans got two second-half goals apiece from Amy Rodriguez and Lindsay Tarpley as they rolled over their CONCACAF rival, which started 10 veterans of the 2007 Women's World Cup. Heather O'Reilly was a terror for the USA, setting up the first three goals from her position on the right side of midfield.
Sundhage said the game was special.
"Of course, I was nervous," she said, "but at halftime, I felt that no matter where you are, this is soccer and that felt good. It's good for my confidence. I'm so happy because it's a good start on our road to [Olympic] qualification and it is a game I always will remember."
She was delighted with the USA's attacking mode.
"For us, it was a good start," she said. "We tried to change the attack a little bit. We weren't successful in the first half with the final pass, but the second half was much better and I am very happy about that."
Sundhage was impressed with Rodriguez, who was making her first start of the USA.
"Her speed is exceptional," said Sundhage, "and the fact that she scored two good goals today is good confidence for her and for the team. There will be different players stepping up at different times and I think that can be one of our strengths. It's not about one player, it's will be about the whole team. There will be different teams, different times and different stars."
There will also be different roles. O'Reilly, normally a striker, took on the role of playmaker.
"I like to usually be on the other team's restraining line," said the former North Carolina star, "and this time I found myself serving the restraining line. Luckily, I connected with Amy Rodriguez on a couple of goals and later to Lindsay Tarpley when she came into the game. As much as I like scoring goals, it was a great feeling to help set up some really nice goals today."
The game also marked the international debuts for right back Ali Krieger and center back Becky Sauerbrunn. Sauerbrunn's first game ended on an unhappy note, however, as she broke her nose in a collision with a Canadian player and had to come off in the second half.
"I'm always going to remember," said Sauerbrunn. "First cap, first broken bone, first win."
In goal, Hope Solo made her first start for the USA since her controversial benching by Sundhage's predecessor, Greg Ryan, at the Women's World Cup.
The USA next faces Finland on Friday. China defeated the Finns, 2-0, on first-half header goals from captain Li Jie and Liu Yali.
Jan. 16 in Guangzhou
USA 4 Canada 0. Goals: Rodriguez 51, 65, Tarpley 71, 78.
USA -- Solo, Chalupny, Sauerbrunn (Cox, 64), Rampone, Krieger, Boxx, Osborne (Hucles, 46), Lloyd (Tarpley, 64), O'Reilly, Rodriguez, Wambach.
Canada -- McLeod, Booth, Chapman (Kyle, 78), Hermus, Rustad, Wilkinson, Franko, Schmidt, Sinclair, Tancredi (Armstrong, 67), Robinson (Filigno, 46).
Referee: Kirsi Savolainen (Finland).
Shots: USA 18, Canada 8
Shots on Goal: USA 11, Canada 2
Saves: USA 2 Canada 5
Corner Kicks: USA 3, Canada 5
Fouls: USA 8, Canada 5
Offside: USA 5, USA 2.