The Manchester City forward was a livewire all night at Wembley as the Three Lions got their Euro 2020 qualifying campaign off to a flier.
And Southgate says he’s not surprised to see Sterling’s attacking endeavours rewarded after seeing him in training all week.
"I thought he was electric all night,” said the England manager.
"He's been like that all week in training. He was involved in four of the goals and it was a great night for him.”
They were Sterling’s first goals at Wembley in four years, since a strike against Lithuania during Euro 2016 qualifying.
But Southgate admits we’re dealing with a much more confident and accomplished player in 2019.
"He's really matured as a person and as a footballer and he's hungry for those goals now,” he added.
"He's determined to get in the right areas of the pitch and the quality of his finishing, he's just hitting things instinctively without thinking too much.
"We've got exciting wide players, we've got the young boys [Jadon Sancho and Callum Hudson-Odoi], Marcus Rashford can play there as well and we've got others in attacking areas too.”
Southgate and his squad now return to St. George’s Park to recover and begin preparations for Monday’s game with Montenegro.