Leeds suffered a second defeat in three games at Birmingham to allow Sheffield United to overtake them in the race for the second automatic promotion spot.
But Bielsa insists he is not seeing any signs of anxiety among his players as the Championship campaign enters the final straight.
Leeds face Preston at 7.45pm on Tuesday night.
“I never watch the team become overcome by nerves,” Bielsa said in his press conference on Monday.
“This team know how to live in difficult moments. They cope well with difficult moments.
“The mind aspect is as important as the physical aspect. A strong mind is needed for a strong physical effort. A strong mind means you can use your physical ability.”
A win over Preston at Deepdale will see Leeds leapfrog back into second with the Blades not due to face Birmingham until 24 hours later.
Bielsa insists they are still focused on securing the target they have fought for all season of winning promotion back to the Premier League for the first time since 2004.
“Our desire to be first or second is a very high motivation because it’s the aim and objective of one year of work,” said the Argentinian.
“In the last part of the season, we want to arrive at this situation and our motivation is higher.”
Bielsa suffered his first loss with Leeds to Preston in the EFL Cup in August and knows Alex Neil’s side will be difficult.
But he says Leeds cannot afford any more slip-ups and that all six of their remaining games are must win.
He added: “In all of the games that we are going to play from now until the end of the season, we have the same conditions – we have to win every game.”
Bielsa also revealed Kemar Roofe will replace Pablo Hernandez if the Spaniard is unfit to face Preston.
Championship fixtures (Tuesday)
Blackburn Rovers v Derby County 19:45
Bolton Wanderers v Middlesbrough 20:00
Bristol City v West Bromwich Albion 19:45
Preston North End v Leeds United 19:45
Sheffield Wednesday v Nottingham Forest 19:45
Swansea City v Stoke City 19:45
Championship fixtures (Wednesday)
Birmingham City v Sheffield United 19:45
Brentford v Ipswich Town 19:45
Hull City v Wigan Athletic 19:45
Millwall v Queens Park Rangers 19:45
Norwich City v Reading 19:45
Rotherham United v Aston Villa 19:45