Goals from Julian Alvarez, Erling Haaland and Phil Foden had us in control at the interval, before a Chris Mepham own-goal shortly after the break made it four.
Jefferson Lerma netted a late consolation for the hosts.
Versatile teenager Lewis, who played the entire 90 minutes, had 91 touches and 93% pass accuracy in a fine display on the south coast.
The Academy graduate was delighted to return to winning ways after successive 1-1 draws with Nottingham Forest and RB Leipzig.
He said: “The best thing to do to come back from a few poor results is to win. It’s the best way to respond. We are gutted not to get a clean sheet but it sends out a message with four goals.
“The early goal set the tone and we carried on going, and we could have had more in the end. It’ll send a message out and we’ll continue to hopefully perform like this and win games like this comfortably.
“I just try to do my best for my team. I’m just pleased to be playing whenever I can.
“I got my rhythm quickly and did as well as I could. Pep [Guardiola] just tells me to play my normal game but asks me to go inside alongside Rodri, to give us more control of the midfield.”
Lewis operates in a flexible role for the team, transitioning between right-back and central midfield under the orders of Guardiola.
The youngster revealed that he thoroughly enjoys the responsibility of the role and is thriving due to his education and guidance throughout his time progressing through the Academy.
“I love playing in this role,” he said. I have played as a midfielder before and then been a full-back so I love it. I get more of the ball in advanced positions and you feel more important to the team. 
“I have played there all the way through the Academy, so it’s comfortable but with these players around you it’s 10 times easier.
“It’s about winning the ball back on the transition. It’s nice that he wants to play me and trusts me, it’s up to me to perform.
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“The players in the dressing room are very experienced and have had it every year, we know to focus on ourselves and that’s the only way.”
