Los Rojiblancos need to win and for Qarabag to at least avoid defeat at Roma at the same time for Diego Simeone’s men to avoid a premature exit and fall into the Europa League.
Costa forced through a return to Atletico after three seasons at Stamford Bridge featuring 59 goals in 120 appearances, plus two Premier League titles, but is ineligible until January due to their transfer embargo and has remained in Madrid to work on his fitness.
“Diego is a huge player. He scores a lot of goals and important goals,” Luis, who returned to Atletico after a single season at Chelsea in 2014-15, said:
“It is frustrating seeing him playing like an animal, but he can’t play. It’s just a month until he can play with us. He’ll help us a lot.
“He came back to Atletico because Chelsea couldn’t keep him because it’s his desire. He really wanted to come back to Atletico.
“He knows the club, he knows the way we play. He has already adapted.
“I know it was difficult times for him and for Chelsea. Now everybody’s happy. We want to see him play and happy again.”
Simeone and Luis insist Atletico’s sole focus will be on beating Chelsea in Champions League Group C.
“We don’t have to be looking about what happens in Rome,” Simeone said. “We just have to think about us.”
Meanwhile Cesc Fabregas says he hopes to fulfil a long-awaited dream by winning the Champions League with Chelsea. Fabregas has won almost every major honour in his storied career with Arsenal, Barcelona, Chelsea and Spain, including the World Cup — but the European Cup is the exception.
Fabregas was initially out of favour last season in Conte’s first campaign. He had made only four appearances at this stage last year; this season it is 18 after he showed his worth.
“Well, I would be lying if I say that I wasn’t worried,” said Fabregas.
“I wasn’t playing, I wasn’t really part of his (Conte’s) initial plans and at that point you can do two things.
“You can just give up and accept you are not going to be part of the team or the club in the future. The other is what I did, put your head down and be humble, show him that he’s wrong.
“My relationship with the manager (now) is fantastic. He trusts me. He knows exactly what I can give to the team.”
Fabregas is a first choice in Conte’s favoured 3-4-3 and 3-5-2 formations, but the 30-year-old playmaker is out of contract in June 2019.
Chelsea’s policy is to offer players 30 and over only 12-month contract extensions, but Fabregas is not concerned by that.
“I am only 30. What is 30? Nothing,” Fabregas added.
“I’m very young. I really mean it. Especially how I play, the position I play. You can go for many more years.
“I’m where I want to be. I’m enjoying my football. When the moment comes to talk about different things I’ll be here, ready for it.”
Conte believes Fabregas has plenty of years remaining at the top.
“He is still young for sure,” the Blues boss said.
“When you are 30 years old you have at least five more years. He’s a winner in his mind, in his mentality, for this reason he is very strong.”
Since the 3-0 loss at Roma, Chelsea have won five of their six games — the draw at Liverpool the exception — scoring 14 goals and conceding twice.
Given the saga surrounding Costa which saw the striker return after three years at Stamford Bridge, Conte was evasive when asked if would give him additional satisfaction to see Atletico slip into the Europa League.
The Italian, who is again without defender David Luiz (knee), said: “I think we must have great respect for Atletico Madrid and for the whole team, not only for one, two, three players. If the whole team after tomorrow’s game has to play Europa League, it can happen.”