Albion have been slow starters under Mel's reign so far, having to come from behind to earn draws with Everton, Liverpool, Chelsea and Fulham at home.
They also gave an early lead to Swansea two weeks ago, only to stage another stirring comeback after the interval to win 2-1 at the Liberty Stadium.
That was Mel's only win from his nine games in charge of the Baggies since replacing Steve Clarke - but he has a big chance to bank three vital points when Ole Gunnar Solskjaer's struggling Bluebirds visit the Midlands.
Cardiff are in 19th place and trail Albion by three points but have played a game more than Mel's men.
They have been poor on their travels so far this season, losing 11 of their 15 games and scoring just eight times while shipping 29 goals.
West Brom have only secured three victories in front of their home fans, having drawn seven and lost five.
But Mel, who met 150 fans at a Q&A session on Wednesday night, wants his troops to fly out of the traps on Saturday.
"We need the spirit we had against Swansea," said the Spaniard.
"We've been conceding too many early goals. We need that extra effort against Cardiff.
"This (relegation) is not a situation that comes into my head. I am far more optimistic.
"For us there is only one game. Cardiff is the 'final'. The only thing that will do for us is a victory."
Youssouf Mulumbu, meanwhile, has reminded the fans of the role they must play in roaring the players on to a vital victory.
He said: "When I'm chasing the ball and I hear my song it refreshes my mind and legs - and I feel like 'I'm going to do this for them'.
"It's all motivation on the pitch; it's really important - and the fans have to know that!
"Even when you win a free-kick or corner and they start shouting we know we are at home and the opponent feels that.
"We need to show Cardiff this is going to be a long afternoon and we're there to win. I hope our fans can make The Hawthorns a scary place for Cardiff."