Spurs won five, drew two and lost just one of their eight Champions League group stage matches – that defeat coming away to holders Paris St-Germain.
However, their Premier League form has been largely poor since November, including a damaging 4-1 defeat by north London rivals Arsenal and a woeful 3-0 loss at relegation-threatened Nottingham Forest.
Last month Frank said he felt trusted by the board but BBC Sport understands he was already under significant internal scrutiny and at least one member of the club’s executive had raised the option of ending his reign.
Tottenham took just 10 points at home in the league under Frank, but had a better away record, claiming 19 points from 13 matches on the road.
Tottenham beat Burnley, Manchester City and West Ham in their opening four league games, while also beating Villarreal in the Champions League. But they could not build on that start and Frank’s style of play never won over fans.
Prior to joining Tottenham, Frank spent seven years in charge of Brentford, guiding the Bees from the Championship to the Premier League in 2021.
Speaking before Brentford’s Premier League home game against Arsenal on Thursday, manager Keith Andrews tipped Frank to bounce back.
Andrews was Frank’s set-piece coach at Brentford before replacing the Dane as head coach when joined Tottenham.
“My initial feeling was that of sadness and basically I hope he’s OK, which I’m sure he will be, but today’s obviously a really tough day for him,” said Andrews.
“Of course I have huge empathy for him and feel for him and his staff at the moment.
“Will he bounce back? I don’t think that’s in doubt. I think he’s proved himself as a really good Premier League manager, so yeah, absolutely.”
Arsenal manager Mikel Arteta, meanwhile, expressed sympathy for Frank.
“Thomas is an excellent coach. He is an extraordinary man as well and he has proven that in the Premier League,” said Arteta.
“We know our responsibility is beyond just performance. Sometimes results dictate what happens to us. I wish him all the very best for whatever he wants to do next.”