Runaway Scottish Premiership leaders Celtic didn't do "the basics of the game well", said manager Brendan Rodgers, after they needed Arne Engels' stoppage-time penalty to rescue a point in a six-goal epic against Dundee.

Tony Docherty's side showed outstanding character to find two equalisers, before Aaron Donnelly's thumping header looked like it was going to secure Dundee a first win over Celtic in 24 years and a first at Dens Park since 1988.

But Mo Sylla's late handball from a Nicolas Kuhn shot meant Engels could send Trevor Carson the wrong way from the spot in an incredible encounter.

And while Rodgers praised his players for their persistence, he was disappointed by their performance.

"We had lots of control in the first 40 minutes, but for our standard, that second half has to be better. We were too passive. Too slow. Not aggressive enough," he said.

"Normally, we've defended very, very well. But for whatever reason, we went soft. They're not perfect, they're not robots. They will, at times, drop the level.

"But tonight was about doing the basics of the game well and we didn't quite do that well enough to keep the clean sheet."

The game had started well for the league leaders, with Luke McCowan opening the scoring on his return to Dens Park, the former Dundee captain heading in superbly from a Greg Taylor cross.

Celtic failed to double their lead through chances for Adam Idah and Paulo Bernardo, who headed off the crossbar, and that allowed Dundee to equalise when Oluwaseun Adewumi finished an electric counter-attack.

Yang Hyun-jun then nodded the visitors back in front after Carson parried Kyogo Furuhashi's dangerous cross towards the back post.

But Docherty's side were again level just a minute later when Cameron Carter-Vickers diverted the superb Josh Mulligan's cross into his own net.

Celtic were rattled for large spells thereafter as a young and fearless Dundee side pushed for a winner, which they thought they had through Donnelly's back-post header in the 78th minute.

But Engels' penalty means Celtic's huge lead at the top stretches to 16 points, while Dundee move to within two points of sixth-placed Hibernian.

Less than a week after earning an impressive point against Rangers at Dens, this result and performance will only fuel Dundee's bid to achieve a top-six finish for the second season running.

Docherty's starting line-up included two teenagers and seven players aged 23 and under, but they were fearless in their approach after riding their luck for the majority of the first half.

Near misses from Ethan Ingram, Finlay Robertson and Adewumi, who continues to look a real find, had Celtic rocking throughout the second period.

Mulligan played an integral part in that with relentless running and quality on the ball.

Much has been made about Lyall Cameron's contract situation - with the midfielder reportedly a target for Rangers - but Mulligan, whose current deal is also up at the end of the season, will surely be attracting interest in this form.

A difficult one to analyse for Celtic, who are still on course to win the title by a huge margin despite dropping two points.

Perhaps a concern for Rodgers will be his side's recent away form. They have now won just one of their last four on the road following a draws against both Dundee clubs, defeat at Rangers and Saturday's victory at Ross County.

That slight, slight blip away from home will almost certainly not hurt their pursuit of another Premiership crown, but Rodgers will be keen to address that, plus their slackness in defence, with big Champions League games on the horizon.

The Celtic boss will also be disappointed by his team's inability to put the game to bed before Dundee grabbed their first equaliser, with Idah's form a worry.

The former Norwich striker, who failed to get on the end of a dangerous Kyogo cross at close range with Celtic one up, is now without a goal in 12 games and was removed on the hour after failing to have a notable impact on the match.

Dundee manager Tony Docherty: "I'm immensely proud, but the overriding feeling is one of disappointment. I thought we did enough to win.

"I watched Celtic put on Kuhn, Engels, Palma... I've asked Lyall Cameron to get off his sickbed to play; Finlay Robertson hasn't trained; Cesar Garza had to come off. To put in that level of performance against that opposition is bordering on heroic.

"We made a Champions League team wobble. We sensed it, we went for it and gave everything to win that match. I thought my players deserved that tonight."

Celtic manager Brendan Rodgers: "We had lots of control in the first 40 minutes, then we give away a needless goal from a counter-attack. That gives them impetus.

"We then get in front, 2-1, and should go on and go through the gears, but we then gave away two really disappointing goals that we should deal with.

"And, of course, then you're fighting right to the end to get something from the game. It was a disappointing result from our perspective."