The Three Lions host Montenegro on November 14 - which will be England's 1,000th worldwide - before travelling to Pristina three days later, with Southgate's side needing just one point to secure their place at Euro 2020.
A point at Wembley against Montenegro in the 1,000th global match for the men's team would be enough to guarantee qualification.
Leicester boss Brendan Rodgers defended his player while Southgate said Maddison would have learned there was an increased spotlight on him. Having said that, I don't think it was a great decision that he took. "We're supporting him because we picked him - now he's got to come into the squad and fight for his place with everyone else".
"He's still on his way back, of course - he's a young player so he's still learning and improving but in the games he's played, you can see his level and he's pushing those players in the wide positions to start in the team".
Leicester City's James Maddison is embraced by manager Brendan Rodgers after being substituted off during the Premier League match with Liverpool at Anfield in Liverpool October 5, 2019.
"But it's good that he's back fit and playing regularly, and he's obviously one of our most experienced defenders".
If Mount misses out Southgate could hand an global lifeline to Tottenham's Alli.
The Liverpool midfielder has scored four goals in his past four games.
The Chelsea youngster was called up to the England Under-21 squad last month following his return from an Achilles injury.
Jack Grealish's form for Aston Villa has not been enough to earn a call up, though Southgate confirmed the midfielder is in line for a place in the squad should any of England's other wide options drop out.