Having at last had a positive result to cheer with victory over Bournemouth, Everton's season hit a new low when they were totally outplayed in a 3-1 loss to new champions Leicester on Saturday.
The Foxes had been celebrating all week and could have been forgiven for being below their best but Everton never threatened to be party-poopers.
Martinez's men will have a say in matters at the bottom of the table on Wednesday, with victory for Sunderland enough to keep them up and relegate Norwich and Newcastle.
But the Toffees boss was keen to reassure fans of the Magpies and Canaries that he expects and demands a much-improved performance.
Martinez said: "The reaction has been clear since the final whistle and we all have a strong desire to get back to our best level and tomorrow is the opportunity we have to show that
"It's a huge, huge game - not just because of what Sunderland are playing for
"I think the integrity of the Premier League has always been the strongest of any league that you're going to see in Europe, and from our point of view it's about reacting from our performance against Leicester. Nothing else
"There's no need for any bigger assurance than we're all fighting and we'll all have to react tomorrow."
Sunderland have hit form at just the right time, taking eight points from their last four games
They go into Wednesday's match on a high after Saturday's 3-2 victory over Chelsea, which made them firm favourites to avoid the drop
Sam Allardyce has hailed the togetherness of his players, while rumours persist about to what degree Everton's squad are pulling for their manager
But Martinez, in an unusually brief press conference, again insisted there are no problems on that score, saying: " It's not such a thing as winning the players back
"Two weeks ago we had a good response, a really good, determined performance, to get a win at home against Bournemouth
"Then we went away to Leicester in a game where we got caught up with the atmosphere and the celebration of a unique footballing achievement, and probably that lack of intensity cost the performance
"But we never lost the fight, we scored late in the game and we always wanted to try to get something out of the game. But if you don't match the intensity of your opponent, it'll be very, very difficult
"Tomorrow that intensity needs to be matched. Sunderland have got a very good record at home in the last six games, they had very good performances, they've got a good continuity in their line-up, so we know exactly what we're going to face."
Everton's cause has not been helped by the goals drying up for leading scorer Romelu Lukaku
The Belgian netted 25 times in his first 37 appearances of the season for the Toffees but has drawn a blank in the last eight matches
Speculation persists about a big move for the 22-year-old this summer, but Martinez insisted Lukaku has not had his head turned
"He loves the game so much that I don't think he's a player that's going to get affected by speculation," said Martinez.
"It is true that it's the first time he has to cope with 47 games in a season
At the age of 22, you're still working out how to get through games and how to cope with the intensity.
"That doesn't mean you feel tired, it's just knowing how to cope with that mental fatigue of refocusing for every game, which is a normal thing that happens when you're a young player."
Martinez at least has a couple more defensive options, with Ramiro Funes Mori back from suspension and Gareth Barry likely to be available after recovering from a groin injury.
But Tony Hibbert, Phil Jagielka, Seamus Coleman and Gerard Deulofeu remain sidelined.
Source: PA