Tim Sherwood has wished Ange Postecoglou well in his new role at Tottenham, while warning that success must be brought instantly.
The Aussie boss was appointed as Spurs manager earlier this week as he departed Celtic after winning the treble with the Hoops.
Postecoglou will officially start in his new role on July 1 and Sherwood reckons he will find the Premier League a far tougher test than the Scottish Premiership.
"They've gone for a few other managers beforehand, it looks like, like it's fell into his lap so good luck to him," Sherwood explained on No Tippy Tappy Football podcast.
"He's done well at Celtic and now he's come to the big league, this is the acid test.
"He will find it a culture shock, there are no ‘gimme’ games, and anyone can beat anyone especially when you are at Spurs. He'll come in with an attacking style of football.
"Without being disrespectful to the Scottish Premier League, you have four games a year and it is not a very competitive environment. The Premier League is the ultimate test.
"It’s a brave move from Tottenham’s point of view, but they have tried to go safe before with [Antonio] Conte and [Jose] Mourinho and it hasn't worked so why not roll the dice? They have certainly done it this time.
"I wish him well.”
Sherwood ended with a warning for Postecoglou adding: “When he sat down with Daniel Levy, I know Daniel would have said ‘we want to be in the Champions League’. It’s going to be very hard to get into the Champions League and if that is the objective, he will be out of a job very soon.”
Meanwhile, Celtic should bring Brendan Rodgers back “in a heartbeat” if their old manager is keen on a return to Glasgow, according to former Hoops full-back Mark Wilson.
Rodgers is favourite to replace Postecoglou currently in the bookies' market.
The former Liverpool manager has previously stated he would be open to a return to Celtic Park if the timing was right, but accepted he might not be welcomed by fans who were hurt by the manner of his sudden exit to Leicester in February 2019 after winning seven domestic trophies out of seven.
There are reports that Rodgers would prefer a longer break after losing his job as Foxes manager in early April but talk of a return is lingering.
“If Celtic have got the option to bring him back, I would in a heartbeat, I really would,” Wilson said.
“Brendan Rodgers is a top-tier manager, his history shows that. You don’t get the Liverpool job if you’re not a top-tier manager, you don’t get the success in Glasgow he had if you’re not a top-class manager.
“He had a style of football here that the supporters and players bought into, possession-based. It was terrific to watch and it yielded trophies, year after year.
“Of course the baggage he has with some Celtic fans, the way he left, would be hard to dissolve. But football is a results-driven business and if he came back and started well, and there were a few good signings in the door, I think a lot of that bad feeling would quickly evaporate.”