England will head to the World Cup on a six-game winless streak, their longest going into a major tournament, but lifted by the eye-catching performance of Jude Bellingham against Germany.
The Three Lions were denied a morale-boosting win in an enthralling 3-3 draw against the four-time world champions at Wembley on Monday.
At just 19, Bellingham stepped forward to help spark a fightback from 2-0 down to 3-2 in the space of 12 second-half minutes.
The Borussia Dortmund midfielder started the move that resulted in Luke Shaw firing in England's first goal from open play in more than 520 minutes.
Bellingham then put his body on the line to win a penalty that Harry Kane converted to complete the comeback before Kai Havertz snatched a late equaliser for the visitors.
"I think the biggest thing is he's got a top-level mentality to compete," said Southgate.
"Yes, he's got technical ability and he's got athletic prowess, but the thing that makes the difference with the top players is that mentality that they are never beaten.
"They drive the game and they don't look like they are fazed by any occasion and that's what we are seeing."
Bellingham was in the England squad that reached a first major tournament final for 55 years at last year's delayed Euro 2020, but spent little time on the pitch.
Southgate's critics have pinpointed a stubbornness and loyalty to players who have performed for him in the past.
That faith proved misplaced in the selection of Harry Maguire, who was at fault for Germany's first two goals, even though the Manchester United captain has been dropped at club level.
Bellingham could also have suffered from Southgate's loyalty to the midfield pair of Declan Rice and Kalvin Phillips, who combined to great effect at Euro 2020.
However, a shoulder injury to Phillips that could rule the Manchester City midfielder out of the World Cup in Qatar gave Bellingham an opportunity at Wembley that he took full advantage of.
A child prodigy, Bellingham made his debut for Birmingham aged just 16.
His boyhood club were mocked for retiring his 22 shirt number when he left the club after just one season in the first team.
"He said he wanted to be a No 10 (creative midfielder). I said, 'I think you can be a 22'," Mike Dodds, Bellingham's long-time academy coach, told The Athletic.
"He asked what I meant and I said, 'You can be a No 4, a No 8 and No 10 — someone who can do it all'."
Despite interest from Manchester United, he chose Dortmund because of the German giants' reputation for developing young talent.
Now into his third season in the Bundesliga, transfer speculation surrounds him again with United, Manchester City and Liverpool expected to battle for his signature next year – Dortmund are reportedly asking for £150 million ($160 million).
"I was impressed when he was 17, imagine now he's 19," said City boss Pep Guardiola after Bellingham scored against his side in the Champions League for the second time earlier this month.
"He's an exceptional player. I think everybody knows it."
Southgate reaffirmed after the Germany match that he is prepared to block out the "noise" from media and fans to show courage in his convictions.
The England boss doubled down on his determination to play three at the back and gave public backing to Maguire and Shaw, who is also struggling for game time at Manchester United.
But, fitness permitting, it is inconceivable that Southgate does not start Bellingham when England open their World Cup campaign against Iran on November 21.
"Build everything around Jude Bellingham," tweeted former England midfielder Jermaine Jenas. "He's got that 'I'm gonna do what I want' type attitude that this team needs!"