Ruud van Nistelrooy acknowledged his new Leicester City side must improve to compete in a "brutal" Premier League, despite Tuesday's 3-1 win over West Ham.

Jamie Vardy opened the scoring after just two minutes of Van Nistelrooy's first game in charge of the Foxes, who added a second from Bilal El Khannouss just past the hour.

Patson Daka's late finish ensured the Dutchman would open with a win at the King Power Stadium, where Niclas Fullkrug produced a stoppage-time consolation for the struggling visitors.

West Ham dominated for large parts of the match, however, and Van Nistelrooy conceded his side must still seek improvements going forward.

"I said after the game, they're buying into some new ideas like the 4-4-2 formation and being very compact and together," the former striker said on Amazon Prime.

"Winning our duels and playing the ball. I think we have the profiles to do ball recoveries and playing forward.

"If we want to get a breather then we need to get possession on a more consistent basis, if not then we get out-pressed."

West Ham had 31 shots in total, their most ever in the Premier League since Opta data began in 2003-04, and accumulated a remarkable 3.09 expected goals (xG).

That illustrates how poor the Hammers' finishing was, and Van Nistelrooy knows similar tests will follow as he bids to keep Leicester in the division.

"We know the Premier League is brutal. We know what our task is," he added. "We also know how much possession and how many shots West Ham had.

"We know how tough the Premier League is and we saw that with the West Ham team, we had to give everything for the three points.

"On a long-term basis, we know the performances need to get better and it's something we have to persist with. The 3-0 was a relief."

Julen Lopetegui cut an understandably frustrated figure after his side passed up a plethora of opportunities.

"It's frustrating because I think we deserved much more," the West Ham boss told Amazon Prime. "It's hard to say this when you lose 3-1 but it's true.

"Normally you have to win this match but we didn't score when we had to do and we suffered after the first goal.

"Football is about goals. It's a hard day for us. Maybe we have to remember this game as a way that we have to build for the next matches.

"I am very frustrated but [on Wednesday] we are looking for the next challenge, knowing that we can change the next situation.

"They [the players] want to win for them, for me, for the club."