José Mourinho has claimed blame for Chelsea’s traumatic campaign does not rest with him alone as his fading champions attempt to avoid the embarrassment of slipping into the Europa League.

The London club confront Porto, with whom Mourinho won the European Cup in 2004, at Stamford Bridge on Wednesday night needing a win to top Group G and a draw to ensure progress to the knockout phase, most likely as runners-up on the assumption Dynamo Kyiv beat the section’s whipping boys, Maccabi Tel Aviv. Yet Chelsea have suffered four home defeats this term, the latest of which, by Bournemouth, left them 14 points from the top four. A fifth would risk condemning them to Europe’s secondary competition.

The relentless domestic toils have heaped more pressure on Mourinho to ensure his team’s involvement in the Champions League – with all its traditional implications for a Chelsea manager’s future – extends into the new year. Yet the Portuguese believes he retains the backing of Roman Abramovich, who witnessed Saturday’s loss first-hand, on the basis of his past achievements at the club and despite results having shown no real improvement since the issuing of an unprecedented public vote of confidence in early October.

Asked why he was convinced of that faith, Mourinho said: “Because I think that I did lots of good things in this club for the owner to know the quality I have, and the owner has shown me that belief twice: once when he brought me back to the club [in 2013]; the second time when he gave me a new contract for four years [in the summer]. I don’t think the owner is a person to change with the wind.

“I know the wind of the results is an important wind. I know this wind is strong because the results in the Premier League are really bad. But I think the owner knows who I am and what I give to the club, and the owner believes that I am the right person to do the job. And now I don’t speak about the owner, but just about the reality of the situation: you can read these bad results and focus everything on the manager. You can look at the results and look to players with performances below acceptable [levels]. You can look to this and look to the unlucky decisions we’re having in every competition, not just the Premier League. And you can look in many directions and decide this is not a one-man responsibility.”

For all that Mourinho may still have support in the boardroom, most notably from the influential director Marina Granovskaia, it is Abramovich alone who will determine whether he is to be retained. The last two managers sacked by the oligarch – Roberto Di Matteo and André Villas-Boas in 2012 – were dismissed with the team’s participation in the Champions League either effectively over or hanging by a thread.

On both occasions, Chelsea’s domestic form had left the owner fearing the club might not finish in the top four with either the Italian or the Portuguese in charge, though neither had endured anything as miserable as the prolonged dip in form suffered by Mourinho’s team this year. Ironically, finishing third in Group G and falling into the secondary competition would arguably offer a better chance of qualifying for next year’s Champions League given the winners of the Europa League gain automatic entry.

Yet Thibaut Courtois suggested demotion would be “embarrassing” because “a team like Chelsea has to have the goal to win the Champions League”. Mourinho, too, has been scathing of the idea of playing in the lesser competition – “It is a different level of competition for a different level of player and club,” he said earlier this season – and has been dismissive of his predecessor Rafael Benítez’s achievement in claiming the trophy in 2013 at the culmination of his interim stewardship. “But there is another way [of qualifying other than winning the Europa League], which is to win the Champions League,” said Mourinho. “It’s harder than winning the Europa League, yes, but this is the competition we’re in.

“I was always against the teams who have been knocked out of the Champions League going into the Europa League because it’s not fair on those who have been in the Europa League all along. If you are knocked out of the Champions League, you should go home and focus on domestic competitions. But those are the rules. We don’t want that. We want to play Champions League, play the best teams – Barcelona, Real Madrid, Bayern, all the big teams. And, for that, we need to win tomorrow.”

Although insistent he is not solely to blame for the team’s struggles, Mourinho appeared to shift the focus on to his misfiring forward line when considering his team’s profligacy. A manager who has previously scorned the trotting out of statistics chose to list a few of his own, suggesting his team had beaten their internal record and scaled new levels of “high intensity work” over the past three games. “We ran and worked more than ever, and at a certain intensity we’d never done before. Our levels of ball possession are much higher than before, too. The number of chances created are higher than ever. But our number of goals is lower than ever. You draw your conclusions.”

The need for Diego Costa, who has scored seven times since January, and Eden Hazard, who has gone 25 club games without a goal, to recover some bite was obvious, with those comments echoes of the manager’s complaints over the forward line of Samuel Eto’o, Fernando Torres and Demba Ba from his first year back at the club in 2013-14. Costa and Hazard will start, with John Terry and Ramires set to be recalled after injury.