World Cup holders France hammered Australia 4-1 to start their title defence and Saudi Arabia inflicted a shocking upset over Argentina 2-1 in perhaps the tournament's biggest surprise so far.
Yahoo News Singapore gathers some of images from these matches.
Giroud joined Thierry Henry as France's all-time leading goalscorer with a brace.
Craig Goodwin put the Socceroos in the lead with a 9th minute goal.
The win leaves Les Blues on top of Group D after Denmark and Tunisia drew 0-0.
Mexico 0 - 0 Poland
Mexican goalkeeper Guillermo Ochoa stood tall between the posts to deny Polish striker Robert Lewandowski's penalty, earning Mexico a share of the spoils with Poland in Group C.
El Tri's 37-year-old Ochoa is playing his fifth World Cup.
Tunisia kicked off with a strong performance against European Championship semifinalist Denmark holding the pre-tournament dark horse to a 0-0 deadlock, three hours after Saudi Arabia upset the mighty Argentina.
Christian Eriksen marked his return to a major tournament football less than a year and a half after his cardiac arrest on the pitch at Euro 2020.
Messi put his team in the lead with a penalty in the 10th minute but the Saudis roared back to life with two goals in the second half.
There was a scary moment during stoppage time after Saudi's Yasser Al-Shahrani took a flying knee to the head from his teammate goalkeeper Mohammed Al-Owais. Al-Shahrani was flattened and appeared unconscious before he was stretchered off.
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Victoria Beckham looked incredible on Instagram wearing a gold, see-through dress to advertise her perfume, Portofino 97 - from her Victoria Beckham Beauty brand.
Jude Bellingham scored a stunning overhead kick in the fifth minute of stoppage time in England vs Slovakia - and Man United icon Roy Keane showed a trademark reaction to the goal
Roy Keane has been a prominent figure in the ITV studio throughout Euro 2024 and he was at it again with a hilarious quip in the build-up to England's last 16 clash
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King Charles is said to be in discussions to visit his estranged son Prince Harry in America for the first time in years - but his wife and Prince William are reportedly not happy