Liverpool manager Jurgen Klopp is interested to see how Jose Mourinho's return to football will pan out, while long-time rival Pep Guardiola believes he will do a good job at Tottenham.
Mourinho is back in the game following his appointment as Mauricio Pochettino's successor, ending an 11-month hiatus since his dismissal as Manchester United boss.
He will renew rivalries with both Liverpool and Manchester City and will be tasked with bringing Spurs closer to those sides during his tenure.
"Welcome back, Jose," Klopp said. "Obviously it's nice to have him back. He was desperate, you could see the time he was not in.
"But on the other side Mauricio is not there any more and that shows you how things change so quickly nowadays.
"About five months ago we played each other in the Champions League final and now he is on holiday – I hope he can enjoy it.
"He did a brilliant job at Tottenham, no one doubts that, an outstanding coach.
"But everyone knows that pretty much all the jobs available – and not available – Mauricio will be in contention.
"When I heard it first I could not believe in that moment, but a couple of moments later there was already a solution. Jose? He is highly motivated, so it will be interesting as well."
Guardiola, who duelled with the former Real Madrid boss when managing Barcelona and City, described his rival as an "incredible manager".
"I think you know him better than me," he said. "He was many years here with different clubs. Welcome back. He is an incredible manager and I'm pretty sure he'll do a good job."
Frank Lampard revealed that he had exchanged messages with his former boss, congratulating him on his appointment.
Lampard was a key player for Chelsea during both of Mourinho's stints at Stamford Bridge and says the Portuguese is inheriting a quality team at Spurs.
"We had a couple of messages to congratulate him on his new role," Lampard said.
"I think in the Premier League having people of such character and quality as Jose Mourinho is a great thing.
"I think we all watched his press conference yesterday waiting for the lines and personality.
"I think history and results speak for themselves. The trophies and titles he's managed to win at the clubs he's worked at are not surprises, it's because of hard work that he's been in and he's done that consistently at the teams that he's been at. That's what we measure him and measure us as managers by."
Lampard, who – like Mourinho once did – has said he would never manage Spurs, added: "Jose Mourinho has managed a lot of football clubs over a long career and sometimes that's what happens.
"So that's his decision and whether fans judge you or not is out of your hands.
"It's something you take those decisions and you see, but as a professional you have to understand the right to work.
"But we do also have this tribal instinct in this country where fans react to that, but that remains to be seen."
Bournemouth manager Eddie Howe, who was briefly linked with replacing Pochettino, has no doubt Mourinho will still produce the goods.
"I was as surprised as everybody else watching from afar what happened this week, but Jose is an unbelievable manager and I think it's great for the league that he's back," Howe said.
"It's probably not ideal timing for us to go to Tottenham in his first (home) league game.
"Look at his record. I'd love his track record, the trophies that he's won, the things he's achieved in the game, it's incredible.
"So, for me, he's one of the all-time greats. I think the trophy cabinet says that. He's certainly got a lot more to give."
