It was also only the fifth time in World Cup history that a team has scored five or more goals in the first half.
The Tottenham striker bagged his third after a 61st minute shot by Ruben Loftus-Cheek hit his foot and bounced over Panama goalkeeper Jaime Penedo.
Intriguingly, it also means they are level on points, goal difference and goals scored with Belgium in Group G. The two sides meet in Kaliningrad on Thursday. Not many players get to score a hat-trick in the World Cup.
"We wouldn't swap him for any other No. 9 in the tournament, such is his ability to take chances", the coach said. But they all count, and long may the 24-year-old's fine scoring form continue.
"Even in St. Petersburg there were still people closing the roads off for us when we were returning to the training base (in nearby Repino) at 5am after the Tunisia game".
Jamie Vardy replaced Kane after 63 minutes while the likes of Marcus Rashford and Danny Welbeck looked on from the substitutes' bench, and Southgate said the players with less game time under their belts in Russian Federation were in his thoughts. We played some really good stuff for 35-40 minutes but then of course the second half was more hard.More news: Amazon Might Have Just Leaked The Date This Years Amazon Prime Day
"It's one to be proud of", he said of the adidas Telstar 18. We knew there was going to be more goals and we showed that confidence to go and get them.
Germany were matched at a high of [30.0] in the World Cup Winner market as it looked like they would either be eliminated, or leave themselves with a mountain to club should they have just drawn the match, but following the win the defending champions are now back into [8.2] third favourites to lift the Jules Rimet trophy.
"And John Stones is such a threat from set-pieces so we're delighted he's got two goals and he'll be buzzing about that".
But Southgate said: "We would want to keep momentum and keep progressing as a team".
"I'm happy with how I played".
"It's odd because I enjoyed the win against Tunisia more - because of the tension and the fact you get over the line", said Southgate.
Brazil are on course to top Group E, while the world champions salvaged their campaign with a last-gasp win over Sweden on Saturday evening.