Ander Herrera felt Manchester United came through a tough examination to move joint top of the Premier League with an ultimately convincing 4-0 win over Everton.
United moved level with rivals Manchester City at the summit - the two teams' records being identical after five games - by producing a late flurry to push the Toffees aside at Old Trafford on Sunday.
Jose Mourinho's men took an early lead through a stunning strike from Antonio Valencia but laboured for large spells before finally striking three more times in the closing seven minutes.
"It was really tough, Everton are a great team," said midfielder Herrera, whose introduction as a 77th-minute substitute gave United fresh impetus for those crucial final stages.
"We should have been winning by at least two goals but you know when you play against Everton you are going to suffer. That is what happened.
"In the second half they had a couple of chances but the best keeper in the world (David de Gea) was there for us. After that we killed the game in the last minutes."
Much was made of the return of Wayne Rooney, United's record goalscorer, to Old Trafford for the first time since his summer move back to Everton.
The former England captain, the day before appearing in court on a drink driving charge, impressed but was unable to drag the Toffees back into the game.
Instead it was Romelu Lukaku, who missed a glaring chance to make it 2-0 in the first half, who stole the show against a former club. Lukaku set up Henrikh Mkhitaryan for United's second after 83 minutes and then scored himself.
Anthony Martial wrapped up the win with a last-minute penalty.
It has been an impressive start to the season by United but Herrera is not getting carried away.
The Spanish midfielder told MUTV: "We are happy, we are top of the table - fighting with Man City at the moment but we know Chelsea, Arsenal, Liverpool, Tottenham, even Everton, they are going to be there."
Despite Everton's spirited performance, the result continued their disappointing sequence.
Ronald Koeman's side have already had to play tough fixtures against City, United, Chelsea and Tottenham, but they have slipped into the bottom three.
Koeman said: "This is football. If you don't like that pressure, please stop - that counts for the players and the manager.
"But we need points, we need a win because a win is the best medicine to grow your confidence.
"If we get the positives from here and show for the next game, I believe we will grow and we will come (good). I am really realistic about what we can achieve for this season."