There had been a small earthquake in Bulgaria on the eve of this tie. For half an hour last night it looked as if there could be a seismic shock for European football. Then Didier Drogba resumed his fine early-season form, striking his first hat-trick for Chelsea as they seized control of Champions' League Group A.
With Barcelona held in north Germany by Werder Bremen, Chelsea go into their latest double-header against the Spanish champions two points clear. They also top the English league and have won their last six matches in all competitions.
All this, said Jose Mourinho, without playing particularly well. "We need to improve," he said. "We are still not playing very, very well, but playing well enough so I am happy."
The only gloomy note for Mourinho is the form of Andrei Shevchenko who has ended those six wins goalless and substituted. It is now just over nine hours of football since he scored at Middlesbrough but his manager is not losing faith. "He just needs a goal," said Mourinho. "I will play him until he scores, be it three, four, five more matches."
It may take that long, to judge from the Ukrainian's display last night but if Shevchenko is struggling to live up to his price tag and reputation, his arrival at Chelsea appears to have spurred Drogba to take his game to a new level. He now has seven goals this season but Mourinho insisted: "Who scores is not important for me. The most important thing is Chelsea go home with three points and top the group. But it is nice for him. He is playing well."
Tuesday's earthquake measured 2.4 on the Richter scale, with an epicentre 130 miles east of the capital. Few noticed. Most were more interested in the European Union's decision to allow Bulgaria to enter on 1 January next year and the possibility of Levski Sofia still being in Europe when they do.
That seems unlikely but they were bold enough to trouble Chelsea in an extraordinarily open game. Mourinho gave John Obi Mikel, the Nigerian teenager controversially signed from Lyn Oslo via Manchester United, his first start in place of the rested Claude Makelele. More surprisingly, Ashley Cole, who needs games to find form, was also omitted, Wayne Bridge returning. John Terry, as expected, was passed fit.
Chelsea hit the woodwork twice in the opening 20 minutes but were also discomfited at the back. Drogba, with a close-range, swivelling volley which struck the bar after 13 minutes, and Michael Ballack, whose 25-yard drive was turned on to the post by Georgi Petkov, were the unfortunate players. Had either of those gone in it would have quietened a roaring crowd given encouragement by a series of early half-chances afforded to Levski.
Drogba's goal was thus timely. Paulo Ferreira's cross from the right was headed to Mikel's feet by Igor Tomasic. Though Petkov parried the shot, Drogba drove in the rebound.
Were Shevchenko showing any form Chelsea would have settled the tie by half-time but, after wasting an earlier pass from Drogba, he fluffed a header from Ballack's 43rd-minute cross.
The interval proved the excuse for several flares to be released but Drogba continued to show an impressive clarity of purpose. Seven minutes into the second half a long ball from Bridge eluded Elin Topuzakov but not Drogba, who took it on his chest then turned to hit a shot which Petkov reached but could not keep out.
Drogba completed his treble with a stroke of luck of the type Shevchenko needs so badly. Lampard attempted a shot from 20 yards and Drogba diverted it inside the near post as he seemed to be attempting to control it.
The game won, Chelsea perhaps eased up and Petr Cech had to make a flurry of good saves before finally being beaten by a fine strike from Mariyan Ognyanov. By then Shevchenko, having put another opportunity over the bar from 20 yards, had been substituted. He smiled to the travelling support as he came off, but he was surely only masking his disappointment at another blank, curtailed, outing.
Levski Sofia (4-2-3-1): Petkov; Milanov, Topuzakov, Tomasic, Wagner; Borimirov (Koprivarov, 78), Eromoigbe; Telkiyski (G Ivanov, 67), Bardon (Ognyanov, 71), S Angelov; Yovov. Substitutes not used: Mihailov (gk), Hristov, Minev,M Ivanov.
Chelsea (4-1-2-1-2): Cech; Ferreira, Terry, Carvalho, Bridge; Essien; Mikel (Kalou 63), Lampard; Ballack; Shevchenko (Wright-Phillips, 82), Drogba (Robben, 70). Substitutes not used: Hilario (gk), A Cole, Makelele, Boulahrouz.
Referee: L Duhamel (France).
* Barcelona had to rely on an 89th-minute shot from Lionel Messi to avoid defeat by Werder Bremen at the Weserstadion. An own goal from Carles Puyol in the 56th minute had put the hosts ahead. Barcelona's Samuel Eto'o could be out for up to three months after suffering a knee injury.Reuse content