Millwall were without a win since August but goals from Shane Ferguson and Tom Elliott cancelled out Tammy Abraham’s early opener in the week Villa parted company with Steve Bruce.
It could have been worse for Villa as Millwall had chances to inflict more pain on them but in the end Harris was just pleased to get the three points.
He said: “It’s a nice feeling. I’m delighted for my players, the players deserved that, they worked tirelessly.
“We dug in, we showed character to come from behind again. We played like a Millwall team at the Den, and that’s important.
“Sometimes you have to go back to basics, remind players what they’re good at, remind the team what individuals are good at.
“We’ve been back to basic on the training pitch and they got their rewards.
“I’ve talked about individuals not being good enough, up to their own standards, but the last two games everyone who’s gone on the pitch has played to the best of their ability.
“It’s no surprise we’ve had two top performances, we should have six points but have four, and that’s the standards they’ve set, and it has to continue.”
Under the stewardship of caretaker boss Kevin MacDonald, it looked like Villa might end the dreadful run of form that has seen them win just one of their last 10 games when they took the lead with their very first opportunity on seven minutes.
After Jack Grealish had been fouled, Conor Hourihane flighted in a perfect free-kick for Abraham to deftly volley home.
MacDonald’s side then began to dominate the game, with Grealish controlling the tempo and looking a cut above the other players on the pitch.
But they created few clear-cut chances and Millwall gradually grew into the contest, and were level on 25 minutes when Shaun Williams delivered a free-kick, Jake Cooper won the header and the ball dropped to Ferguson who rifled in his first goal of the season via a deflection.
Millwall were ahead in the 48th minute when Villa only half-cleared a corner, leading to something of a goalmouth scramble when the ball was returned into the six-yard box, and it dropped to Elliott, who hammered home through Orjan Nyland’s legs.
MacDonald said: “I’m disappointed not to come away with something.
“First half we started reasonably well and having scored the goal we thought we were in control.
“But we knew we were always going to be under pressure from set-pieces at Millwall.
“They got themselves back into the game and scored a good goal to equalise. And we never really started in the second half.”
MacDonald also warned the new manager has plenty of work on his hands to turn things around at Villa Park.
He added: “I think there are lots of things the new manager will need to address. All the players, individually, need to tidy themselves up. The team as a group need to tidy themselves up.
“There are individual mistakes from a different player each game. I’m sure it will get tidied up very quickly. If it does, this team will go up the table very quickly.”