Coutinho has been one of Liverpool's key performers this season and he hailed the resilience that Klopp has instilled in the squad.
Liverpool host Sunderland at Anfield on Saturday and victory would keep the pressure up on leaders Chelsea, who face Tottenham Hotspur in the day's late kick-off.
Brazil international Coutinho has been one of Liverpool's key performers this season and he hailed the resilience that Klopp has instilled in the squad.
"This used to be a team that didn't really believe in itself," said Coutinho, whose side could only draw 0-0 at Southampton last weekend.
"Now the players feel more comfortable and this comes from the coach. That's something that's reflected on the pitch and in the results.
"I like the tactical training we are doing. There is a lot of it. He (Klopp) is teaching us to press when we don't have the ball and keeping that pressure up.
"Then we have to keep possession when we do have the ball. It's all about the confidence and the mentality that the coach has given us."
Sunderland have won their last two Premier League games, against Bournemouth and Hull City, having not managed a solitary victory in their previous 10 league matches.
It has lifted David Moyes's team off the foot of the table and Klopp thinks it is essential Liverpool do not just turn up and assume they will come away with a win.
"The most important thing is to get confidence and Sunderland have it now," said the German.
"It's like the points are already won and we couldn't be further away from having the points already. We will not underestimate them, 100 percent not.
"If one person in the stadium would underestimate them, it would be the first mistake we could make."
Klopp is again set to be without midfielder Adam Lallana, who is still struggling with the groin injury he picked up on international duty with England.
Sunderland must record their first win at Anfield since 1983 if they are to make it three consecutive Premier League wins, as they bid to boost their latest battle against relegation.
The Wearsiders, who have not recorded a hat-trick of top-flight victories for two and a half years, are trying to climb out of the drop zone for the first time since mid-September.
Manager Moyes must decide between Steven Pienaar, Seb Larsson and Jan Kirchhoff to replace Northern Ireland midfielder Paddy McNair, who has been ruled out for the season with knee ligament damage.
Black Cats captain John O'Shea is also pushing for a return in central defence, in place of the suspended Papy Djilobodji.
Jason Denayer, the on-loan Manchester City defender, has urged his team-mates to seize the opportunity to make history at Anfield.
"It would be nice to say we were the first Sunderland team to win at Liverpool for more than 30 years," said the 21-year-old Belgium international.
"We'll go there in a positive mood after our last two results and we'll see what happens. We can't afford to have a losing mindset. We'll give it a go."