Manager Brendan Rodgers said Celtic proved their “winning mentality” by defeating Partick Thistle to extend an unbeaten domestic run to 21 games.
Scott Sinclair scored the only goal on Tuesday to move Celtic 14 points clear at the top of the Scottish Premiership.
“You need to have character and that resilience. They’re two of the real key factors in top sides,” said Rodgers.
“Whenever you’re not at your highest level but you get the result, it shows you have another ingredient.
Celtic’s winner came after 16 minutes and the champions might have added to their advantage after the break if it had not been for a series of saves from Tomas Cerny.
However, the hosts looked edgy at times in defence and Thistle, who are bottom of the table, created several chances to equalise, leading to a tense finish.
“We’ve shown our qualities throughout many games this season, and we showed another side to our performance, which is that ability to stay together when you maybe aren’t playing as fluently as you have been,” Rodgers told BBC Scotland.
“When we failed to take our chances and it stays at 1-0 then of course it’s always a little bit hairy towards the end.
“I didn’t think in the first half that our pressing was good enough. At times we passed it around but our intensity wasn’t there. Second half we were much better.
“Partick are a good side, I don’t know how they’re bottom of the league because they play really well and they’ve got good energy.
“So I have to give massive credit to the players for that persistence and energy to keep going.”
Rodgers made eight changes to his starting line-up, including a debut for Calvin Miller, who he compared to England defender Ryan Bertrand before the match.
The 18-year-old left-back played for almost 60 minutes before being replaced by Emilio Izaguirre, having looked comfortable at times but also outmuscled on occasion by David Amoo.
“That was one of the reasons for putting him in,” Rodgers said. “We felt Amoo, who was quick and strong, would be a good test for where Calvin is at. He did very well.
“Physically it’s a different challenge for him, a couple of the duels he lost out on, but I was impressed with his composure. He can be very proud of his performance.
“Now we see his reaction, what he takes away from the game, and hopefully he can continue to improve.”
Thistle pressed and harried Celtic, something their manager Alan Archibald felt his side failed to do when they lost 4-1 to Rodgers’ team at Firhill on 9 December.
“The players put in a really good shift at a tough place to come,” said assistant manager Scott Paterson.
“We created a few chances and gave them a scare. We rode our luck a couple of times as well, but Tomas [Cerny] had a lot of saves to make from outside the box. We’re disappointed to lose a goal from a set-play.
“The good thing is that we’re creating chances, but we now have to make them count.
“We need the points, but we’ve still got that belief in the dressing room. The players are all together.”