England open their European Championship campaign with a Group D clash against Croatia at Wembley on Sunday.

The Three Lions will be looking for revenge after being beaten in the 2018 World Cup semi-final by Croatia.

Ahead of the game, the PA news agency takes a look at some of the key talking points.

Past meetings

Gareth Southgate's England were knocked out of the 2018 World Cup by Croatia.
Gareth Southgate’s England were knocked out of the 2018 World Cup by Croatia (Adam Davy/PA)

The aforementioned defeat in Moscow three years ago will still be a sore memory for much of the England squad.

Kieran Trippier’s early free-kick had Gareth Southgate’s side ahead only for Ivan Perisic to equalise and Mario Mandzukic to send Croatia through to the final.

Since then, the teams have clashed in the Nations League – a 0-0 draw behind closed doors in Rijeka followed up by Jesse Lingard and Harry Kane scoring late goals in a 2-1 Wembley win to send England into the inaugural finals.

Jeers for the knee?

England players continue to take the knee before matches.
England players continue to take the knee before matches (Lee Smith/PA)

The mixed reaction to England players taking the knee before their last two fixtures has made front- and back-page headlines.

Prime Minister Boris Johnson has called for supporters not to jeer the anti-racism gesture ahead of Sunday’s game.

That plea is likely to fall on deaf ears, although Southgate has said his players will continue to defy the boos to make the stance.

Shape of things to come

Concerns over the fitness of Harry Maguire have led to conversations about how England will set up at the back.
Concerns over the fitness of Harry Maguire have led to conversations about how England will set up at the back (Andy Rain/PA)

Southgate played a back four in both warm-up wins over Austria and Romania but has been known to switch to a three-man defence against stronger opposition.

The run to the final four in Russia was also built on a central defensive trio and it remains to be seen how Southgate will deploy his troops against Croatia.

The fitness of Harry Maguire may figure into Southgate’s thinking, with the Manchester United captain back in training following an ankle injury.

Forward thinking

The likes of Raheem Sterling and Jadon Sancho are battling it out to start England's opening fixture.
The likes of Raheem Sterling and Jadon Sancho are battling it out to start England’s opening fixture (Steven Paston/PA)

The way Southgate lines up his defence will have an impact on which attacking talent he can call upon.

While captain Harry Kane is a guaranteed starter, behind him England are blessed with some fine options.

The likes of Marcus Rashford, Raheem Sterling, Jadon Sancho, Bukayo Saka, Phil Foden and Jack Grealish are all in contention to start – but a handful are destined to be disappointed.

Hey Jude

Jude Bellingham became England's third-youngest senior international when he made his debut last year.
Jude Bellingham became England’s third-youngest senior international when he made his debut last year (Nick Potts/PA)

There are also selection headaches in Southgate’s midfield, with Liverpool skipper Jordan Henderson having played just 45 minutes of football since February.

Declan Rice is expected to start with Kalvin Phillips also in contention – but the form of 17-year-old Jude Bellingham will not have been overlooked by the England coaching staff.

The Borussia Dortmund teenager enjoyed a fine season in Germany and was named the Bundesliga’s newcomer of the year and Southgate would be making something of a statement by selecting the former Birmingham man.