Ralph Hasenhuttl felt Southampton's serious approach was the reason behind an eight-goal thrashing of Newport and a new club-record away win.
Saints boss Hasenhuttl had entered the second-round Carabao Cup tie wary of Newport's giant-killing reputation, with several Premier League clubs having fallen at Rodney Parade in recent years.
But Southampton – who have suffered high-profile 9-0 Premier League defeats to Leicester and Manchester United in the last two seasons – enjoyed a goal-fest of their own in south Wales.
Mohamed Elyounoussi grabbed a hat-trick and Armando Broja scored twice, while Nathan Tella, Kyle Walker-Peters and Nathan Redmond also netted as Southampton matched their biggest victory since World War I.
"I think this was a very deserved win," Hasenhuttl said.
"It was a serious performance from the first minute, this is what you need against a lower-league club.
"To get so early three goals up allowed us to push and keep the tempo high, then we could score a lot of goals.
"It's not easy. You have to take it seriously and have a clear plan.
"We managed it quite well but do not hang it too high, it's a lower-league team. A lot of teams have struggled here in the past."
Chelsea loanee Broja was on the scoresheet nine minutes into his Saints debut and again showed his finishing instincts with a classy second-half strike.
Southampton were 3-0 up at the break and Elyounoussi, who has spent the last two seasons on loan at Celtic, grabbed a second-half hat-trick.
It was the Norway international's first goals for Southampton since his £16million move from Basel in 2018.
"Armando did a good job," Hasenhuttl said.
"Moi scored three goals. It was not a surprise because I know him.
"We had a lot of different scorers. This is what we need, more players scoring more goals."
Newport manager Michael Flynn was absent after testing positive for coronavirus and his influence was badly missed by the Sky Bet League Two side.
Assistant manager Wayne Hatswell said: "It was a harsh lesson and that was the calibre of team that we were up against.
"Fair play to Ralph, he brought a really strong team. They pressed us high up the pitch and we saw the difference in quality.
"It's not going to define our season playing Southampton, we've got a really big game coming up against Salford now and that has always been in the back of our minds.
"We've been able to get a rest into some players and we were mindful that Saturday is important as well.
"One became two very quickly and all of a sudden it deflated us. I was more disappointed with the second-half performance because our heads went down a little bit."
