Jude Bellingham has been called up to the England squad for the first time following the withdrawal of James Ward-Prowse and Trent Alexander-Arnold through injury.
The 17-year-old midfielder was originally included in the U21 squad, but will now link up with the senior team ahead of the games against Republic of Ireland, Belgium and Iceland.
Bellingham has impressed since making a summer switch from Birmingham City to Dortmund, featuring in 10 matches, scoring once.
It caps an incredible rise for Bellingham, who only finished his first full campaign of senior football last season.
During his debut season with Birmingham, Bellingham became a lynchpin of his boyhood club's midfield and featured 44 times, scoring four goals.
Despite being without Ward-Prowse and Alexander-Arnold, England manager Gareth Southgate is hopeful he will be able to call upon Marcus Rashford.
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The striker is scheduled to report for duty on Thursday to allow for further assessment on an injury sustained in Manchester United's 3-1 victory over Everton last Saturday.
The majority of the squad arrived at St. George's Park on Monday with Ben Chilwell, Eric Dier, Harry Kane, Kyle Walker, Joe Gomez, Jordan Henderson and Raheem Sterling due to report on Tuesday.
England face Republic of Ireland at Wembley on Thursday before travelling to Belgium on Sunday and welcoming Iceland on Wednesday to complete UEFA Nations League Group A2.
Sky Sports News reported on Monday England may have to forfeit their final Nations League group game against Iceland, with UEFA expected to sanction Denmark's fixture with the Icelanders on Sunday.
Currently, the UK Government will not allow any of Iceland's players into the country to play the game if they have been in Denmark - where a new strain of coronavirus has been linked to the country's mink farms.
Elsewhere, England U21 manager Aidy Boothroyd has added Everton duo Ben Godfrey and Tom Davies to his squad, but will be without Norwich defender Max Aarons for the matches against Andorra on Friday and Albania on Tuesday.
Analysis: 'Southgate determined to fast-track Bellingham'
Sky Sports News reporter Rob Dorsett:
Jude Bellingham isn't old enough to drive in Germany. He's dropped off by his mum at the Borussia Dortmund training ground each morning. Now, he's in the England senior squad, aged 17.
It has been an extraordinary rise for the Stourbridge-born teenager, and Gareth Southgate expects him to take this next step in his capable stride, just as he has done with every other "first" that has come his way.
Two months ago, we were reporting the then extraordinary news that he had jumped four age groups to be called up for England's U21s for the first time. That was just after his £25m move to Dortmund, where he became the most expensive 17 year old ever.
He made his Bundesliga debut, on September 14, and scored. At the age of 17 years and 77 days, he became the club's youngest goal scorer for 68 years.
Before that, he'd said an emotional farewell to Birmingham City, who took the unprecedented step of retiring his number 22 shirt in his honour - something that had never happened before, not even for the club's favourite son, Trevor Francis.
Southgate doesn't have a plethora of midfield options to choose from, and Bellingham is the closest thing he has to a traditional "number 8" - a box to box midfielder, who can win the ball, and score and create goals that can also win England a game.
Now, he'll be training alongside Harry Kane, Raheem Sterling, Harry Maguire for the first time. And don't be surprised if he makes his England debut at some point against Republic of Ireland on Thursday night - Southgate and the FA are determined to fast-track Bellingham, because they see him as a key player for the national team's (not too distant) future.
'Arsenal were close to signing Bellingham'
Former England captain Tony Adams says Arsenal were close to signing Jude Bellingham from Birmingham but the transfer slipped through the net.
"I think it got lost this one, in the transition of the chief scout at Arsenal going out," said Adams.
"He was spotted very early on, not by me, but by the Arsenal recruitment office.
"The chief scout was absolutely bowled over by him (Bellingham) and the great prospect that he is.
"The sporting director Edu, coming from Brazil had no European and UK experience and I think it got lost in the transition.
"Unfortunately the chief scout had the deal in place but we missed that one.
"He's a great talent but unfortunately he hasn't joined the right club."