Southgate, who feels the win will bode his young squad well for future challenges, was particularly happy with the contribution of his front three, Sterling (who ended a 27-game wait for an worldwide goal), Rashford and Harry Kane.
Jordan Pickford was often in the spotlight in the Group A4 encounter at Real Betis' Estadio Benito Villamarin, where he played a key role in the Three Lions' opening two goals before nearly gifting Spain a way back through his overconfidence.
Journalist Xavier Bosch claims that Alcacer would still not play at Barcelona despite his fine recent form, while deputy director Josep M. Artells analysed the players and why they did not connect as they should on the field, with Kane again the English focus with a "masterly" performance.
Hard to pick one for this game as, in spite of the late concession, all of England's players did pretty well.More news: Hunter kills British mountain biker in French Alps
A Raheem Sterling double and a Marcus Rashford goal put the Three Lions in command over their hosts in Seville in what was a breathtaking first-half performance.
'The other day [against Croatia] we played some good football at times, but today I think we played really well and took those chances when we needed to.
La Roja fought back after the break to eventually lose 3-2 in Seville. Only the group victor moves on. Spain totalled 25 attempts and 70 percent of possession, and blew it.
Chelsea's trigger-happy defender Marcos Alonso had to great opportunities to score in either half, forcing an early save from Jordan Pickford while scores were still locked at zero and hitting the bar with a shot near the end. Rashford sent a nice ball into space for Sterling, who entered the area with only the goalkeeper to beat and found the top of the net with a superb finish.More news: Liverpool injury latest on Salah, Milner and Van Dijk
"It was a attractive feeling", Sterling said.
Sterling admits the pressure he was under all came out in his emphatic goal celebration, and says he is now focused on causing more "havoc" in an England shirt.
"We knew today, the way that Spain press, you have to get the first couple of passes out of that press spot on".More news: Huawei Mate 20 Pro vs Samsung Galaxy Note 9