Everton manager Roberto Martinez has warned his players not to underestimate struggling Sunderland when the Toffees look to maintain their push for a top-four finish at the Stadium of Light on Saturday.

The Black Cats are at the bottom of the Premier League table, seven points from safety, and look strong candidates to be relegated to the Championship following Monday's woeful 5-1 thrashing at Tottenham.

On paper they would appear to be ideal opponents for fifth-placed Everton, who have their sights on a top-four finish which would earn them a place in next season's Champions League.

Victory at the Stadium of Light would see them climb above fourth-placed Arsenal, who were beaten 3-0 by Everton last weekend but don't have a league fixture on Saturday due to their FA Cup semi-final against Wigan.

However, Martinez believes that the Toffees will face a Sunderland side who will not feel under pressure because their survival hopes have been written off, therefore potentially making them dangerous opponents.

"You get to a point in a relegation battle where you've got nothing to lose," Martinez said.

"Sunderland are in a position now where they have got seven finals and they are going to approach it in that manner.

"They have had significant performances at home in the league this season -- Manchester City to mention just one. They can replicate that level any time, as they showed in the League Cup when they were phenomenal.

"That's going to make it a really exciting and tense game. The small margins are going to be vital, so we need to recover well.

"The demands last Sunday in the 3-0 win against Arsenal were huge, but psychologically the whole football club senses a real feel-good factor and that's something we need to use in our advantage."

Martinez will check on midfielder Leon Osman, who has a deep cut near his eye, while captain Phil Jagielka will miss out as he recovers from a hamstring problem.

Sunderland's slim hopes of avoiding relegation have taken another major blow with injured striker Steven Fletcher set to miss the rest of the season.

The Scotland international has missed the last four games after damaging ankle ligaments in the draw against Crystal Palace in March.

It is the latest in a string of injury worries suffered this season by the forward, who has made just 16 starts, scoring three times after also being sidelined with shoulder and Achilles problems.

The 26-year-old hoped to make it back for the final month of the campaign to help the Black Cats' struggle to avoid relegation.

But the former Burnley and Wolves target man will now turn his attention to getting fit for the start of next season -- when Sunderland are likely to be in the Championship.

Head coach Gus Poyet admitted: "It's not good and it's going to be difficult for him to return this season."

Poyet is short of options up front after losing faith with US international Jozy Altidore and England Under-21 striker Connor Wickham.

January arrival Ignacio Scocco has failed to shine due to a lack of match fitness, leaving winger Adam Johnson to be pressed into service as a makeshift striker alongside on-loan Liverpool forward Fabio Borini.

The Black Cats have taken just one point since the Tyne-Wear derby triumph at Newcastle on February 1, and Poyet added on Fletcher's hopes of a comeback: "I'm not giving up on Steven returning this season, but maybe that's just me.

"At the moment though, it's difficult to say."