The value of Barkley and the Premier League's top scorer Romelu Lukaku, who netted twice in the 4-2 success, was evident as the Toffees ended the Foxes' six-game winning sequence since Craig Shakespeare replaced Claudio Ranieri in February.

However, the long-term future of both Everton stars remains uncertain, with Lukaku publicly stating his desire to play in the Champions League and win silverware and Barkley in the final 18 months of his contract.

Asked what can be done to ensure Liverpudlian Barkley remains with the blue half of Merseyside, Koeman said: "We offer him a new contract, and then (there are) two possibilities.

"One, he signs that contract, if he doesn't sign that contract then we need to sell the player. It's simple, it's not so difficult in my opinion."

The duo combined brilliantly for Lukaku's first of the afternoon which saw him score for the eighth successive home fixture in 2017, and his 23rd Premier League goal in the second half capped a comfortable success.

Both he and Barkley came under fire for underwhelming performances against Liverpool and then Manchester United but this was a reminder that the future looks bright at Goodison provided Everton's dangermen stay on board.

"We try to keep the best players," Koeman added.

"We spoke a lot about Ross and Rom because they are really important. We know Rom is a great finisher but Ross played really good football between the lines.

"I think he should have scored one but it is what you like to see - your best players performing like they showed because they played outstanding, the whole team performance was outstanding."

Many of Leicester's key players were not involved at Goodison Park as Shakespeare tasted defeat for the first time since being drafted in.

A win would have seen him join Carlo Ancelotti and Pep Guardiola as the only managers to win their first six Premier League games, yet Shakespeare showed that Wednesday's Champions League trip to Atletico Madrid was of more importance than any personal landmark by making five changes.

"The team selection was with the games coming up in mind," he said.

"We've got a lot of games - Wednesday, Saturday, Tuesday. We have got a good squad and players have had to be patient.

"The idea was whatever team we put out, it was to be competitive and try and win the game. The team selection was to get three points, it was more about squad rotation rather than anything else.

"I don't think (Leicester have lost their momentum). Footballers are resilient. The players are resilient. I've just said to them in there, 'We have been on a really good run. We have to start again and go another run'."