A trio of Arsenal players were involved as Germany thrashed Portugal in Group G, while a host of Chelsea talents were in the starting line-up as Nigeria drew 0-0 with Iran
Thomas Muller scored a hat-trick but there was an Arsenal flavour to Joachim Low's side, while Chelsea and Manchester United were also represented.
There were also a number of Chelsea players involved as Nigeria drew with Iran, and there were more familiar faces in USA's victory over Ghana.
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Ozil’s indifferent club form had filtered on to the international stage following several lacklustre displays during Germany’s warm-up fixtures but, against an accommodating Portugal defence, he was back to the sort of form which saw him shoot to prominence four years ago in South Africa.
The German’s movement was intelligent, his running off the ball purposeful, while he was typically accurate and economical in possession. Whether drifting out to the left or gliding through the middle Ozil was a constant menace and the only black mark on an otherwise encouraging hour-long appearance was the second-half miss which saw him shoot too close to Rui Patricio when clean through on goal.
Ozil's Arsenal team-mate, Lukas Podolski, was introduced with under 10 minutes to play in place of hat-trick hero Thomas Muller but had little time to make a significant impact.
The towering centre-half assumed increased responsibility at Arsenal last season, marshalling a defence that improved markedly thanks to his organisational skills and reading of the game.
With Mats Hummels an injury doubt for Germany’s second match of the tournament, Mertesacker’s leadership and experience will be vital going forward.
The 29-year-old, however, was rarely tested by a limp Portugal attack which, Cristiano Ronaldo aside, carried little threat and never managed to expose a lack of pace which has long been regarded as Mertesacker’s weakness. Tougher tests surely lie ahead.
The Chelsea man has become accustomed to the role of impact substitute since his move from Bayer Leverkusen to Stamford Bridge so it is perhaps no surprise that he was able to slip so easily into the pace of the game after his introduction as a 63rd minute substitute.
The powerful forward set-up a glorious chance for Morio Gotze following a lung-bursting run before creating Thomas Muller’s hat-trick goal with a driven low cross which goalkeeper Patricio ought to have held.
It came as no surprise that Nani, who made only three appearances for Manchester United in 2014, showed signs of ring rust during a hugely disappointing afternoon for the Portuguese.
The maverick winger threatened early on with a thumping shot from 25 yards which whistled over Manuel Neuer’s crossbar.
Thereafter, his performance was memorable only for the misplaced pass which drew a look of disgust from Cristiano Ronaldo and his comical collision with team-mate Fabio Coentrao which rather summed up his - and Portugal's - disappointing day.
|JOHN OBI MIKEL
A holding midfielder by trade for Chelsea, John Obi Mikel is afforded more freedom on international duty with Nigeria, but failed to make the most of it against Iran despite coming up against little resistance.
Mikel is widely expected to leave Stamford Bridge this summer, and failed to produce a display that would likely convince Jose Mourinho to change his mind.
The Chelsea forward - who spent last season on loan with Liverpool - started brightly for Nigeria, operating from the left wing and running at the Iran back four on a handful of occasions.
Moses failed to make a breakthrough however, and was replaced in the second half by Shola Ameobi, who was recently released by Newcastle United and is currently without a club.
Ameobi himself had a chance to break the deadlock in stoppage time, but saw his header forced out for a corner.
The Stoke City striker started on the bench as Ramon Azeez was given a place in the starting XI, but replaced the youngster with just over 20 minutes to play.
Odemwingie injected some much-needed energy into the game late on, but could not help his side find a winning goal. The striker appeared to have created a scoring opportunity by bringing the ball down with his shoulder, but saw a free kick given against him for handball.
The 20 year old centre-back spent last season on loan at Championship side Middlesbrough and has recently signed a new contract at Stamford Bridge.
Omeruo was preferred to veteran centre-back Joseph Yobo in the starting XI and was rarely tested by Iran, who created few chances throughout a cagey game.
Despite a difficult season in the Premier League with Sunderland, Jozy Altidore was selected by Jurgen Klinsmann as part of the USA's starting line-up to face Ghana.
USA took the lead after 32 seconds through former Fulham and Tottenham man Clint Dempsey, and Altidore had the chance to double their advantage but saw a shot from close range blocked by the Ghana back four.
However, his involvement in the game lasted just 21 minutes as the striker pulled up with what appeared to be a hamstring problem while chasing a loose ball.
The injury could prove to be the end of Altidore's World Cup, leaving Klinsmann with a selection headache ahead of the clash with Portugal on Sunday.
The Everton veteran looked to be in for a quiet night against Ghana after a first half in which he made just one save, racing out to collect the ball and deny Asamoah Gyan a shot on goal from close range.
But with time running out following a string of stops, Howard was finally beaten by Andre Ayew, who latched on to a clever Gyan back heel to drive the ball home at the USA goalkeeper's near post with the outside of his left boot.
Fortunately for Howard, USA went back in front just over four minutes later as John Brooks rose highest to head in a corner as Klinsmann's side claimed the three points.
Like Howard, Geoff Cameron had a quiet first half in defence for USA, forming a solid centre-back partnership with Matt Besler.
Asamoah Gyan started to cause the Stoke City defender and his team-mates some problems in the second half and Ghana eventually scored through Andre Ayew, but Cameron had a solid game as the African side failed to trouble USA from wide areas.
Ghana focused most of their attacking efforts on their right flank against the USA and, as a result, Chelsea youngster Christian Atsu was heavily involved.
Atsu, who was signed by Chelsea last summer before spending the season on loan with Vitesse in the Netherlands, saw plenty of action on the right wing and was comfortable playing the ball with both feet.
But while it was an encouraging display from the winger, his delivery was lacking as Ghana fell behind early and struggled to create genuine opportunities to equalise for the majority.
Atsu was eventually replaced by Middlesborough's Albert Adomah, who played a part in Ghana's only goal in the 2-1 defeat.