After a 2-2 draw with Sevilla in their Group E opener, Liverpool drew 1-1 away to Spartak Moscow on Tuesday, with Fernando's free-kick for the hosts cancelled out by a brilliantly constructed Philippe Coutinho equaliser.
Liverpool now trail leaders Sevilla by two points, but with four games still to come, Klopp is relaxed about his team's situation. "Of course I saw enough (to suggest Liverpool can qualify)," Klopp told reporters at Moscow's Otkrytiye Arena.
"We know more about the two teams. We know Moscow had a lot of injury problems. For sure Quincy Promes will be back for the next game and a few other really good players, which will change their game.
"In football you can never be sure. Yes, we are strong enough to go through, but we have to do it. When the door is open, you still have to walk through. "The door's not even open.
You can see only a little bit of light behind. But we will be ready to go through.
"Because the boys work really hard and you can see that they really want it. You have sometimes situations like this.
Stay cool, carry on, work hard and you will succeed at the end." Fernando put Spartak ahead with a 25-yard free-kick in the 23rd minute, but their lead lasted just eight minutes as Coutinho exchanged passes with Sadio Mane before coolly netting an equaliser.
Despite dominating the second half, Liverpool could not find a winner, with substitute Daniel Sturridge and Mohamed Salah both squandering excellent late chances. Klopp aligned Coutinho, Mane, Salah and Roberto Firmino for the first time, but he said his 'Fab Four' would need time to develop an understanding.
"It's good when you have all these players around, but it's not lining up the players and hoping something will happen -- they all need rhythm and need to be in good shape
and all that stuff," said the German.
"It was a very intense game. For me it's not about the names, it's really about how we can perform. "In a lot of moments we performed as good as possible, in a lot of moments not. We have to keep on working."
Asked why Liverpool had been unable to procure a second goal, Klopp replied: "It's a big question. "Because of a little bit being unlucky, good saves from both goalkeepers and wrong decisions in the decisive moment.
"That's how football is. The only way you can change is to do it again, do it again, do it again, and that's what we'll do." Klopp's "both goalkeepers" remark reflected the fact
Spartak goalkeeper Artem Rebrov had been taken off on a mechanised medical cart mid-way through the second half, with Aleksandr Selikhov taking his place.
Rebrov sustained suspected knee ligament damage and will undergo tests on Wednesday.
Several Spartak players went down with cramp during the second half, but coach Massimo Carrera said that was more a reflection on the effort they had put in than their physical condition.
"Those who haven't played football don't understand it," said the Italian. "Against such skilful players as Liverpool have, we had to run a lot. That's why we got some cramps."
Carrera previously worked under Antonio Conte at Juventus and in an intriguing comment, he said a pre-match conversation with the Chelsea manager had informed his side's approach against Liverpool.
"We spoke only a couple of minutes and it was mostly things I have already observed," said Carrera. "But those pieces (of information) helped me to get this draw against Liverpool."