As Chelsea enter the most pivotal week of Jose Mourinho's second stint with the club, Dan Levene looks at how a defeat could perversely be the best outcome for the club, but the worst for its manager.

If, as former Prime Minister Harold Wilson said, a week is a long time in politics, then a day is an age in football management. Even more so at Chelsea, where 90 minutes can often be an eternity for any coaching career. This week, Chelsea have a series of potentially season-defining matters and Jose Mourinho's future could not be more in the balance.

After the humiliation of home defeat to Bournemouth, the next seven days look set to lay out a pathway for the remainder of the season: with draws at home in the FA Cup, and in European club competitions as well as a trip to table-topping Leicester City in the Premier League.

But it is Wednesday night's visit to Stamford Bridge of Porto which is most crucial to the Blues' season – standing, as it does, between Chelsea and progression in the Champions League. The permutations are many and complex. But the rule of thumb is pretty much this: win, and Chelsea top the group; lose, and they come third, and are bound for the Europa League.

That would result in a big slice of humble pie for Mourinho, who shortly after his reappointment as Chelsea boss in 2013 insisted he didn't want to win the Europa League, or even play in the competition.

That was a clear slight at Rafael Benitez, whose achievement in bringing just that trophy back to Stamford Bridge from Amsterdam was so pivotal in assembling the interim coach’s CV for his present role at Real Madrid.

But the Europa League is certainly Chelsea's best opportunity of getting back into next season's Champions League – with Mourinho having more or less admitted fourth place in the Premier League will be a leap too far.

Mourinho knows and admits the luck involved in winning the Champions League itself, and he has had more opportunities to look back on that good and bad fortune than almost any boss in the game.

But few can see past Barcelona, who now look an even better side than the one that romped to glory in Berlin's Olympiastadion in June.

They could await Chelsea in the knockout stages, should the Blues qualify – as could Paris Saint-Germain or Atletico Madrid, who ended their hopes in each of the last two seasons.

Drop to the Europa League, and the options broaden to include Molde of Norway, possibly Midtjylland of Denmark, and a trip beyond the Black Sea to Krasnodar of Russia.

Yet, in the eyes of UEFA now, the winners of the two trophies are equal – each earning a place in next season's Champions League.

One tough route to remain in the top club of European sides – with the income and attractiveness to players associated with it. One Thursday night meander around the broader continent's also-ran title-holders, for the same ultimate prize.

A no brainer in competitive terms – but what would defeat to Porto do to Mourinho's immediate job prospects? Should he battle through that, there is the matter on Monday of motoring up the M1 to the King Power Stadium.

The very man he first deposed as Blues boss, Claudio Ranieri, awaits with tables somewhat turned. Mourinho says he has given up on targets, and wants simply to win the next match. Given the stakes at play here, is impossible to know whether those who run Chelsea feel the same way about that.

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