The hosts shot to the top of Pool A in what was a rematch of the 2018 final and the only match of the opening day in California.

Canada broke the deadlock after three minutes when Ryan Lee converted from Jeff Teat's pass.

The score went back and fourth up until the conclusion of the first half with the teams going into the break level at 4-4.

However, a third-period flurry put the US up 7-4 with Brennan O'Neill completing his hat-trick 51 seconds before the end of the segment.

Josh Byrne scored a consolation goal for the Canadians, with Teat putting up another assist, but it was too little too late as the match came to a close 20 seconds later.

The US were good value for their victory as they led the charts on shots, ground balls, face-offs, and saves while being equal for turnovers and clears.

Half-time in the Championship's curtain-raiser saw DJ Steve Aoki perform after the Opening Ceremony took place before the match with a "vibrant display of international sportsmanship, culture and a parade of nations".

The US has won a record 10 world titles since the first edition of the tournament in 1967.

The country is looking to become the first to win back-to-back gold medals in more than 20 years.

The trophy has changed hands between the US and Canada every time since 2002.

Competition is set to continue tomorrow in San Diego with 11 matches scheduled.

England versus Australia, also in Pool A, represents the match of the day as the two teams finished fifth and fourth respectively at the 2018 Championship.