Didier Drogba's scriptwriter should take a bow. The Ivory Coast striker set about restoring his reputation in European competition after the infamous histrionics against Barcelona after the semi-final back in May, and his late goals thrust Chelsea into the knockout phase. A perfect record in the section may have been surrendered, but Carlo Ancelotti's team have been offered a reminder that they will benefit hugely from Drogba's rehabilitation.

The forward's form this season has been supremely impressive, with his timing last night just as impeccable. There have been 11 goals already this term, defences shrinking in his presence all too readily as he batters beyond centre-halves at will. Manchester United may be more vulnerable at the heart of their defence than anywhere else, moreover, and that suggests Chelsea will sense further reward when the teams meet at Stamford Bridge on Sunday.

Certainly, the striker's post-match claim that he is currently enjoying the best form of his career may send shivers of apprehension through United's ranks. "A few years ago I was playing with the same confidence, but I think this is my best," offered Drogba. "I always score when I play injury-free. There wasn't anything special about being back again in the Champions League, but I'm just enjoying playing with my friends out on the pitch."

Chelsea had actually progressed smoothly enough to the top of Group D without their talismanic forward, whose furious reaction to elimination against Barça had prompted a three-game Uefa suspension, but he will add a new dimension to them for the more testing stages of this competition.

Indeed this game might have edged away from Chelsea only for Drogba's class to tell in the final eight minutes. "For sure I wouldn't want to swap him for any other striker in the world at the moment," said Ancelotti. "He is playing in a 'good moment' right now, and I hope that can continue."

His performances show no signs of dipping. Chelsea had actually been in danger of losing their air of invincibility in the group, trailing to their first concession in the competition, when Drogba thumped in a header from Florent Malouda's left-wing cross eight minutes from time. That deflated Atlético, their brittle confidence fractured once again, with Juanito and Pablo Ibáñez duly wilting as the striker rampaged on to Ashley Cole's pass. The African then muscled his way towards goal as the centre-backs crumpled, smacking his first shot at the prone Sergio Asenjo then calmly converting the rebound.

Chelsea were effectively through with that goal, even if one final sting remained in the contest. Sergio Agüero, rested initially with Sunday's derby against Real Madrid in mind, had emerged from the bench to fire Atlético ahead with a stunningly executed volley at the far post after John Terry's misguided clearance. That was the home side's first goal of the group, illuminating what had been a dull encounter and hinting at unlikely victory for a while, particularly given the visitors had only managed to rouse themselves in fits and starts on an awkward surface.

Yet Agüero would be required to provide a second glimpse of his class. The game had lurched into stoppage time and the stands were emptying as the home support drifted away dejected and apparently defeated when the Argentinian thrashed a wonderful free-kick into the top corner from some 25 yards. Scouts from the continent's top clubs have filed regularly on Agüero in recent years.

"I like him," said Ancelotti. Asked whether he would delight in pairing him with Drogba, perhaps if Chelsea's transfer ban is frozen in January, he added: "I think Agüero can play with Drogba, for sure."

Chelsea departed mildly annoyed to have surrendered parity when Drogba's efforts should have earned a fourth consecutive victory in the group, though they will be heartened to extend their unbeaten, year-long Champions League run.

"Perhaps we could have done better with the defensive wall, and maybe avoided conceding the free-kick as well," said Drogba. "It's really frustrating to concede a goal like that after the effort we produced. But we can be pleased with what we have achieved.

"We were also thinking about Sunday's game [against United]. We did everything we had to do tonight, and now it is important for us to beat United at home. We have to improve and show different qualities, and be better than we were in Madrid. But I think we still put in a good game. It wasn't a poor performance. We played well, but it wasn't enough to win."

In the grand scheme of things, that matters little. Drogba is back and Chelsea are in the knockout stage, with aspirations that they may return to Madrid and the Bernabéu in May very much intact.