No 1-ranked Germany led after just 24 seconds and 3-0 at halftime but had to hang on for a 3-2 Pool A win over New Zealand. The Netherlands, playing with only half the starters who lost the gold medal game at London in August, scored two second-half goals to beat Pakistan 3-1 after trailing early in the Pool B match.
Australia, trying to win the Champions Trophy for the fifth consecutive time, led 3-0 and beat Belgium 4-2 despite Sebastien Dockier's pair of goals two minutes apart shortly after halftime in the Pool B match.
On Sunday, Belgium play Pakistan, England takes on Germany, the Netherlands play Australia and India will try to make it two in a row when it plays New Zealand.
In Australia's first major tournament since losing its No. 1 ranking after the Olympics, the home side squandered its early lead.
"The first-game blues. We got a result, let's put it that way,'' said Australia assistant coach Graham Reid. "There were five or six minutes where we were quite poor. We were a little rusty, but there were good signs there.''
Australia led 2-0 at halftime through Glenn Simpson's sixth minute goal and another from rookie Jacob Whetton on 29 minutes. When striker Russell Ford added a third two minutes after halftime following a sweeping downfield move, Australia looked on course for a regulation win.
But after Dockier's quick goals, the Belgians created a number of penalty corners and outplayed the hosts most of the rest of the match.
With eight minutes left, Chris Ciriello overcame a broken nose suffered earlier in the match to score from a penalty corner to give his side the clinching goal.
Ciriello's nose was fractured in the first half when one of his high-speed drag flicks rebounded off a Belgian player's stick and hit him in the face.