Bukayo Saka scored twice as England thrashed Iran 6-2 to open their World Cup campaign in style on Monday in Qatar.
Teenager Jude Bellingham, Raheem Sterling, Marcus Rashford and Jack Grealish were also on target as England eased to an emphatic victory in Doha to underline their title credentials.
Mehdi Taremi scored both consolation goals for Iran, the second a penalty.
Maguire, who has been out of favour at club side Manchester United this season, started alongside John Stones in a back four, with Southgate opting against his usual three-man backline for the encounter at Khalifa International Stadium.
England were without midfielder James Maddison, who was nursing a knee injury, while Bukayo Saka and Raheem Sterling played in a three-man frontline with captain Harry Kane.
Azmoun has not played since injuring his calf at the start of October.
England: Jordan Pickford, John Stones, Harry Maguire, Kieran Trippier, Declan Rice, Jude Bellingham, Mason Mount, Luke Shaw, Bukayo Saka, Harry Kane, Raheem Sterling
Iran: Alireza Beiranvand, Sadegh Moharrami, Ehsan Hajsafi, Milad Mohammadi, Alireza Jahanbakhsh, Morteza Pouraliganji, Mehdi Taremi, Rouzbeh Cheshmi, Ali Karimi, Majid Hosseini, Ahmad Nourollahi