Liverpool travel to face the St James' Park side managed by former Reds boss Rafael Benitez a point behind Premier League leaders Manchester City with two matches to go.
Victory on Saturday would see Liverpool go back to the top of the table and ramp up the pressure on City ahead of the reigning champions' home match against Leicester on Monday.
The German manager told reporters at his pre-match press conference on Friday he was expecting a tough game against Newcastle, who are safe from relegation.
But he said his players had proved their ability to perform under pressure all season, amassing 91 points so far with just a single defeat in the Premier League.
"The boys are completely on fire," he said. "When you are in the race and you see you can win it, you don't get tired, that's how it is.
"We are ambitious like hell. We want to (win) but we still know it's not 100 percent in our hands but the only thing we can do is to beat Newcastle and that is unbelievably difficult."
Klopp reiterated that a mature away performance in the Champions League was not reflected in the 3-0 scoreline at Camp Nou.
And he insisted that his players were in a positive mood and had the mental strength to recover as they look to win Liverpool's first English title of the Premier League since 1990.
"It's no problem, of course we have to prove it again tomorrow, but we didn't have to pick up players in Barcelona and give them a hug," he said.
"It doesn't happen too often, honestly, that I lose 3-0 and have much more positive thoughts about the game than negative, but it was in this game.
"When we flew home it was all OK, the boys were already (focused) on the Newcastle game 100 percent," the German boss added.
"The boys have had 20 hours to recover, now we will have one session and try to prepare them for Newcastle, which is important because it will be a different game obviously, but it's not new for us."
Klopp revealed however that Naby Keita would miss the rest of the season with an adductor injury that is set to sideline the Guinea international midfielder for around eight weeks, putting his participation in the Africa Cup of Nations in jeopardy.
Keita limped off midway through the first half in Barcelona.
"Bad news, he has a high-grade adductor injury," said Klopp. "The tendon is ruptured, which keeps him out for at least two months.
"Bad news for us obviously, but bad news for Guinea as well because the Africa Cup of Nations is coming up."