The reigning Premier League champions are on an 11-game unbeaten run in all competitions following the sacking of Jose Mourinho, but sit 13th in the table and trail fourth-placed Manchester City by 17 points.
Nevertheless, Courtois feels all is not lost and is hopeful success in a major cup competition can make up for their catastrophic title defence.
"After the game against Newcastle next week, we play in the Champions League and FA Cup against two great sides [Paris Saint-Germain and Manchester City] and we have to try to win those games because the only way to save our season is to reach the final in one or both of them," the Belgium international told the club's official website.
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"The confidence is good, in the last three or four games we've barely conceded a goal.
"We have the confidence to go to PSG and win the game; we know it's really difficult, last year we had a really tough game there but we want to get a good result to bring back to Stamford Bridge and finish it here."
The first leg of the Champions League round of 16 tie takes place at the Parc des Princes on February 16, with the return at Stamford Bridge scheduled for March 9.