Roberto Martinez has paid tribute to the start former Everton defender Slaven Bilic has made to life at West Ham United and says his side are in for a "terrific challenge" at Upton Park this weekend.
Since Bilic took over, the Hammers have leapt to the upper echelons of the Premier League table and currently sit in sixth.
They have recorded creditable victories over Manchester City, Arsenal and Chelsea so far, using a brand of easy on the eye, attacking football.
And Martinez says Bilic must take credit for the way he has quickly marked his stamp on Saturday's opponents.
“Slaven plays in a very different way to the one West Ham used to play," said Martinez of the man who spent three years at Goodison Park in the late 1990s. "As an ex-Evertonian, we know he is a competitive man. He gained invaluable experience when managing Croatia and his teams are always ready to compete.
“From a psychological point of view, to go to places like Manchester City, Arsenal and Chelsea and win shows they have a fantastic mentality.”
Summer signing Dimitri Payet has been at the heart of much of West Ham's early-season success, netting five goals in 13 appearances.
And Martinez believes shrewd work in the transfer market has also boosted a Hammers squad that finished 12th last season.
He added: “When you bring in players from abroad it is always a gamble in terms of how long it takes for them to settle in. Last season, West Ham had a couple of players in Enner Valencia and Diafra Sakho who had an incredible impact straight away. You can say the same about Dimitri Payet.
“Likewise, Manuel Lanzini has been a very impressive player, and then you have those who know the Premier League inside out, like Victor Moses, who give a level that everyone expects.
"So they have a very good mixture at West Ham and their new signings have come in with a fresh mentality."
Everton, meanwhile, head for East London off the back of a resounding 6-2 home win over Sunderland on Sunday.
However, while Martinez was delighted with the attacking play of his team, he says the lessons to be learned were in defence, as the Black Cats were allowed to recover from 2-0 down to level just minutes into the second half.
“As we all know as a team, defensively we need to be better,” he said. “That is not just the back four and the goalkeeper, it’s the whole team. And that is where the work is.
"We want to be perfect in every performance, we want to be an attacking team. But we will never go out with the intention of keeping a clean sheet in the hope of winning a game because we want to try to find a way to score goals and be a good team to watch.”