Bielsa saluted a deserved victory at Pride Park but insisted the semi-final with Derby was far from over, despite Leeds dominating Frank Lampard’s team and having the benefit of home advantage next week.
Leeds quelled a capacity crowd and struck on 55 minutes when Kemar Roofe drove in his 15th goal of the season and his fourth against Derby.
County struggled to compete and saw the award of a penalty by referee Craig Pawson overturned when his assistant, Eddie Smart, advised the official that Jack Harrison had not been guilty of fouling Jayden Bogle.
Derby, who lost both regular league games to Leeds, travel to Elland Road on Wednesday with the odds against them mounting but Bielsa maintained a focused tone at the end of a convincing afternoon, saying the Champions League fightbacks mounted by Liverpool and Tottenham Hotspur in midweek should encourage his players to be cautious.
“It’s an advantage but it’s not a decisive advantage,” Bielsa said.
“We still have 90 minutes to play and we only have a difference of one goal. If we take as a reference what happened in the last Champions League games, we shouldn’t draw conclusions about it.
"Every game is a new situation and I don't think the three games we’ve played (against Derby) guarantee us anything in the next game.”
Leeds signed of their 46-game term by taking one point from their last four matches, a costly dip which cost the club automatic promotion from the Championship.
Bielsa’s players raised themselves impressively, however, to move within 90 minutes of the play-off final and a clash with either Aston Villa or West Bromwich Albion at Wembley.
Villa lead West Brom 2-1 after an eventful semi-final first leg at Villa Park earlier.
“It was painful for us not to be automatically promoted,” Bielsa said, “but we took the play-offs as a very important opportunity and I think we should value the opportunity of having a new possibility (to be promoted).
“It was a deserved win. Apart from the first minutes of the first half and then 10 or 15 minutes in the second half, we dominated the ball, we defended well, we created danger and we had chances to be more dangerous. When we had to attack we attacked well and when we had to defend we defended well.”
Lampard voiced disappointment with his team’s display, admitting they had failed to impose themselves on Leeds.
“They’re above us in the league for a reason and their team is full of experience, full of really good players at this level,” Lampard said. “The majority of our players are having their first season and when the pressure ramps up it can be difficult to deal with that. If you keep turning the ball over, teams will get control.
“They’re more favourites now than they were before the game. It’s a challenge.”