New Fulham boss Felix Magath's reign at Craven Cottage began with a 1-1 draw at West Brom, and following his arrival Holtby made his team-mates aware of the 60-year-old's fearsome reputation.
Magath managed eight clubs in his native Germany over a 17-year period, and whilst there were trophies and cups along the way, he also acquired a certain infamy.
Magath is renowned for his gruelling training sessions, acquiring other monikers such as 'Saddam Hussein' and 'Medicine-ball Magath'.
The latter refers to tales of Magath forcing his players to run up a hill with a medicine ball as part of their strength conditioning.
As a teenager at the start of his career, Holtby worked under Magath for almost two seasons at Schalke prior to the latter's sacking in March 2011, so knows only too well of the man and his methods.
"I can't say anything negative about him," said Holtby, on loan to the Cottagers from Tottenham.
"When I was at Schalke, for me it was very important to have him as a manager.
"He built my character and made me grow up very quickly with the hard training, getting mentally and physically right.
"He toughened me up as a person mentally. When you're 18 you grow pretty quickly. That's stayed with me until now.
"I know lots of the press have called him very bad names and I don't think it's right to do that. That's over the line.
"It's a bit of a disgrace if you call someone Saddam. It's not like he killed anyone. He's not a murderer.
"Of course he trains hard, but everyone has his own philosophy. He has his own style of training and you have to respect that, along with the fact he won a couple of titles in Germany.
"As a player it was really hard back in the day. I've witnessed a lot of things. I'm not saying we didn't suffer, but I'm not complaining.
"The thing is you have to graft through it. You have to be happy he makes you fit and mentally very strong."
With regard to tipping off his team-mates, Holtby said: "We talked about what could happen and that training is going to be very hard.
"You have to be honest about that, but the most important thing is to be physically and mentally on the top level."
Holtby served as Magath's intermediary during the game, passing on instructions because of his fluency in German despite Magath's reasonable command of English.
Despite the turbulence being felt at Fulham, and with Magath given little time to impress himself on the players, Holtby believes the club will stay up.
"Of course, it's difficult for a manager and players in the middle of a season. We're in a dump," said Holtby.
"He has come in with a philosophy and it's hard to adapt, but you have to do it as quickly as possible.
"It's going to be a tough challenge for both sides, but I think we can do it by getting our heads together and thinking about the situation where we have to stay up.
"I have always said we have the quality needed to stay up."
Fulham appeared poised to secure a rare win on the back of Ashkan Dejagah's 28th-minute strike, until a howler from goalkeeper Maarten Stekelenburg four minutes from time gifted Albion a point.
After making a number of fine saves, Stekelenburg allowed a close-range shot from Matej Vydra to squirm under his body and over the line, with the new goalline technology aiding referee Mike Dean.
For Albion, it was the fourth successive home game under new manager Pepe Mel where they had come back from a goal down to salvage a point.
But after six matches without a win overall under his leadership, Mel knows he and his players need a victory.
"One point is one point, and it's an important point," said Mel.
"I am confident I will keep West Brom up. The players are playing well for me, and are performing every day."