There has been little time to waste following a period of dramatic change at the club.
Former head coach Eddie Howe has moved on while key players Alexander Isak, Bruno Guimaraes, Sandro Tonali and Anthony Gordon have all left in the last year.
Gallows humour gripped some supporters who made the trip after they adapted a chant which once featured the names of Guimaraes and Isak, who are now with Arsenal and Liverpool.
“We’ve got someone in the middle,” they sang. “He knows exactly what we need. [Sven] Botman at the back, someone in attack, Newcastle are going to win the Premier League.”
But it is not hard to imagine those blanks being filled in as a new generation steps up.
The average age of the squad has been dramatically lowered and, on Saturday, forward Harvey Barnes was the oldest starter at the age of 28.
It felt like a potential sign of things to come as goalkeeper Lukas Hornicek, 24, midfielder Aladji Bamba, 20 and forward Toure, 20, made their debuts while 18-year-old Steur impressed from the bench.
Jaissle has a history of developing young players at RB Salzburg, which was a big draw for Newcastle, and he knows better than most what they need.
“Time is the key,” Jaissle said. “They’re young lads. It’s never going to be easy in football, especially at the highest level, but we’re here to do that.”
Malick Thiaw was among the elder statesmen as he led Newcastle out as captain on his 25th birthday and this side will certainly need youthful vigour to play Jaissle’s intense brand of football.
Jaissle was a vocal presence throughout on Saturday, urging the visitors up the field, and rarely stood within the markings of his technical area.
He was even running down the touchline in tandem with his players as they advanced on goal at times.
Just as there is a fine balance to strike on the field, so, too is there one off it.
Newcastle are in the market for additional experience, particularly in the middle of the park, and veterans Dan Burn and Fabian Schar will remain important voices in the dressing room.
But Jaissle has also shown the first sign of a ruthless streak.
Nick Pope was a pivotal figure under his predecessor, but the German left the 34-year-old out of the squad altogether against Valencia.
“I had a talk with Nick,” Jaissle said. “I really appreciate what he did in his career so far.
“He knows exactly the situation right now and we need to deal with it in the best possible way, but I always appreciate the player and the human being behind.”
It has been a whirlwind first week in Spain andJaissle now returns Newcastle for the first time as the club’s head coach.
The 38-year-old already has a landmark in mind to see before he is formally unveiled at St James’ Park next week.
“For sure I will be visiting the stadium and getting my first impressions,” he said.