Enzo Maresca's side were in danger of an embarrassing loss at the Tofiq Bahramov Stadium in Baku after falling behind in the first half.

Estevao Willian gave Chelsea an early lead but Leandro Andrade equalised before Marko Jankovic converted a penalty to give the Azerbaijani minnows hope of a famous upset.

Former Manchester United winger Garnacho came off the bench to bail out the Blues with his composed finish after the interval.

Both sides have seven points from their first four matches in the league phase, leaving them in contention for the top eight finish that secures automatic qualification for the last 16.

While two-time European champions Chelsea have spent over £1.5 billion ($1.9 billion) on new signings in the last three seasons, Qarabag's total transfer outlay since 2020 is less than £7 million.

Despite that financial disparity, Chelsea found it hard to subdue their spirited hosts and they made the five-and-half-hour trip home still without a Champions League away win since October 2022.

Mockingly nicknamed "carrier bag" on their disappointing debut in the Champions League group stage eight years ago, Qarabag have proved a surprise package in this season's competition.

They staged a superb comeback to win 3-2 at Benfica, then beat Copenhagen 2-0 at home and Chelsea were the latest to find them a tough nut to crack.

Chelsea's players were kept on UK time while in Baku to mitigate the effects of the four-hour time difference ahead of Saturday's Premier League clash with Wolves at Stamford Bridge, which is less than 72 hours after they return to London.

The Blues didn't arrive in Baku until the early hours of Wednesday morning, so Maresca made seven changes from Saturday's win at Tottenham in a bid to keep his team fresh.

- Garnacho to the rescue -

Estevao gave Chelsea's inexperienced team a deserved lead in the 16th minute after a vibrant opening.

Picked out by Andrey Santos' pass, Estevao shifted the ball onto his left foot and hit a low drive from 12 yards that beat Qarabag keeper Mateusz Kochalski at his near post.

It was the precocious 18-year-old's fourth goal in all competitions this season.

Brazil forward Estevao is the third-youngest player in Champions League history to score in each of his first two starts in the tournament behind Ethan Nwaneri and Kylian Mbappe.

But Chelsea failed to build on that promising start and they were punished for sloppy defending in the 29th minute.

Camilo Duran stole possession from Chelsea defender Jorrel Hato and cut inside Tosin Adarabioyo for a shot that cannoned back off the post to Leandro Andrade, who slotted a clinical finish into the far corner.

Qarabag had the momentum and they struck again in the 39th minute as Chelsea's lack of experience started to show.

The hapless Hato lost possession on the edge of his own area and conceded a penalty after blocking Duran's cross with his outstretched arm.

Jankovic sent Robert Sanchez the wrong way from the spot to leave Chelsea in disarray at the interval.

Maresca introduced Garnacho, Enzo Fernandez and Liam Delap for the second half and the triple change paid instant dividends.

Delap picked out Garnacho and the 21-year-old lashed a fierce strike past Kochalski from the edge of the area for his second goal since arriving in August.

Fernandez almost emulated Garnacho's impact with an instinctive snap-shot that Kochalski tipped over.

Chelsea laid seige to the Qarabag goal in the dying minutes, but Fernandez drilled narrowly over from distance before Garnacho's close-range effort was repelled by Kochalski.