London. Pep Guardiola's bid to win the Champions League for the first time since 2011 will come under threat from his old friend Mauricio Pochettino when Manchester City face Tottenham in the quarter-final second leg later on Wednesday.
Guardiola's side must overturn a 1-0 first-leg deficit at the Etihad Stadium to avoid extending their manager's frustrating Champions League run.
Guardiola is rightly regarded as the best manager of his generation after trophy-laden spells with Barcelona, Bayern Munich and now City.
But despite having access to vast financial backing at all three clubs and coaching some of the world's greatest players, Guardiola has only got his hands on the Champions League trophy twice in his 11-year managerial career.
The Spaniard won it with Barcelona in 2009 and 2011, while also earning a winners' medal as a Barca player in 1992.
Some critics see that as a meagre return and the only flaw on Guardiola's CV, placing more pressure on the City manager to lead the English champions to their first ever Champions League success this term.
Aware of the harsh prism through which his European record is viewed, Guardiola went on the defensive when asked on Tuesday if he had extra motivation to win the competition again.
"The Champions League is tough. We fail all the time. Sorry guys, I'm a failure!" he said in an outburst laced with sarcasm.
"Not winning the Champions League in Bayern Munich was a big failure. What can I say?
"Do I have to win it? No. The chairman said I have to win the Champions League three times in a row!
"I didn't come here to win the Champions League honestly. I came here to play the way we played the last 20 months.
"The Premier League is the most important title, to be there every three days competing."
Guardiola's mood throughout a rather tetchy press conference ahead of the Tottenham showdown hinted at the strain he is feeling as City chase an unprecedented quadruple.
They have already won the League Cup, reached the FA Cup final and sit two points behind Liverpool in the Premier League with a game in hand.
- Crunch time -
Yet City's history bid could evaporate in the space of seven days if they lose to Tottenham and then fail to take maximum points from Premier League matches against Spurs and Manchester United.
"Definitely. If we don't win these games we will be out of two competitions. I've had this feeling for weeks," Guardiola said.
City's chances of advancing to their first Champions League semi-final in Guardiola's three-year reign have been boosted by the ankle injury that has ruled out Tottenham striker Harry Kane, while midfielder Dele Alli faces a late test on his fractured hand.
But Tottenham boss Pochettino insists his team still have a puncher's chance of holding onto the advantage given to them by Son Heung-min's first-leg winner.
"It is difficult when Manchester City plays a final like they will in this game," he said.
"For us to beat them in the first leg was an amazing result, but the tie is still open.
"What we have is the belief. We are going to fight and hope for a very good performance. You need a bit of luck in important moments in the game."
It is a tie with special meaning for Pochettino and Guardiola after they and several of their backroom staffs became friends during their time managing Espanyol and Barcelona respectively.
"The challenge is Guardiola is maybe the best manager in the world," Pochettino said.
"At the same time it is nice to see them. We met in Spain when we played and managed. We have friends in their coaching staff.
"I think he won 25 trophies. He is the most successful manager in the last 10 years for sure. For me, to win a title with Tottenham is a massive dream."