"The players were spot on. We didn't play the best but we showed character. Robin was one of the 14 players who did their job. He wants to learn more and has fantastic attributes," said Sheringham.
Goalscorer Robin Singh couldn't last the ninety minutes and had to be replaced due to an injury.
"His injury looks serious. He has gone over his ankle; he has a bad knee as well. I'm not sure how long it might take but it looked bad."
The former Manchester United striker was impressed with his team's attitude against Mumbai City, especially in the second half when the home side started to exert more pressure on the ATK defence.
"I liked the team's performance. We changed things around. We shuffled the pack due to injuries. As long as we have enough fit players, I'm happy. From a team's performance, you only get it by digging deep."
"We were comfortable in the first half going forward. Things changed after the goal; that was the game changer. Mumbai changed things after the goal and we dug deep. I liked that character."
ATK substitute Shankar Sampingiraj barged into Everton Santos inside the box late in the second half and despite appeals from Mumbai players, the referee waved the play on. Sheringham took sides with the referee after the game, adjudging the clash not worthy of a penalty.
"Sometimes decisions go for you, sometimes they don't. If wasn't a penalty from my position, not from where I was standing," declared the ATK head coach.
Ryan Taylor ran the show in midfield for the Kolkata-based club against Mumbai City. The former Newcastle United player was brought in as a replacement for the injured Carl Baker.
"When I got Baker in, I thought he was the perfect acquisition, the final piece of the jigsaw. He had a bad calf, he has been written off for three months. We found Ryan as a replacement and I thought he was fantastic. He understood what had to be done."
Debjit Majumder had a fine day in goal for the defending champions, pulling off good saves whenever required throughout the game, He kept out the home side twice in the dying moments of the game to secure the three points for the visitors.
"We knew it was going to be a physical game - Mumbai have that attribute. Debjit has come in for criticism recently but he's worked hard. When you work hard you deserve the reward. His double saves were pleasing; I'm very delighted."
ATK will now return to Kolkata for their home game against strugglers Delhi Dynamos on December 23.