Pep Guardiola's 100th Champions League game in charge of Manchester City ended in disappointment after the much-changed hosts were stunned by Bayer Leverkusen.

Guardiola made 10 changes following their Premier League loss at Newcastle on Saturday, but the decision backfired in calamitous fashion as they fell to back-to-back defeats.

City had started on the front foot with Nathan Ake's poked effort from close range tipped wide by Mark Flekken's sharp reflex save but for large periods after the hosts were slow and ponderous in possession.

Leverkusen were showing signs of speed on the break and got their reward on the counter when Christian Kofane clipped the ball back for captain Alejandro Grimaldo to drill home a crisp first-time finish.

City's fringe players were finding it difficult to maintain any rhythm as they looked to claw their way back into the game, with Tijjani Reijnders dribbling through but shooting straight at ex-Brentford goalkeeper Flekken.

And Kasper Hjulmand's visitors were in dreamland when they doubled their lead on 54 minutes as Czech striker Patrik Schick leapt highest to glance home a header from Ibrahim Maza's pinpoint cross.

Star man Erling Haaland was introduced on the hour mark and almost made an impact 10 minutes later by latching on to Phil Foden's pass, but the ball was smothered at his feet by Flekken.

City were left frustrated when the Norwegian hooked another effort over, but the night belonged to Leverkusen and their joyous travelling support.

Sloppy City pay the price

Guardiola said on Friday that the season started then following the conclusion of the last international break of the year, but City are yet to get going since the resumption.

They would have been expected to bounce back after suffering defeat at St James' Park at the weekend, but the Spaniard made a glut of changes to his starting line-up, much to the surprise of most in attendance at Etihad Stadium.

It led to a disjointed showing from the English side and fringe players such as Omar Marmoush, Oscar Bobb and Savinho failed to take the opportunity offered to them in the front three.

Haaland, Phil Foden and Rayan Cherki were all introduced in the second half as Guardiola attempted to rescue a result, but their run of 13 consecutive home victories against German opposition in this competition abruptly came to a halt.

With three league phase games remaining, this could prove to be a damaging loss for City, dropping them down to sixth in the table. They will find themselves out of the top eight if results go against them in Wednesday's fixtures, dropping at least for now into the places that go into a playoff round rather than straight through to the last 16.

Impressive Leverkusen show efficiency

Leverkusen were in disarray at the start of the season.

The Bundesliga side lost manager Xabi Alonso to Real Madrid and important players such as Florian Wirtz, Jeremie Frimpong, Amine Adli, Granit Xhaka and Piero Hincapie were all sold in the summer.

Ex-Manchester United manager Erik ten Hag came in but his tenure lasted only two league games before being sacked and they turned to Kasper Hjulmand.

The former Denmark manager, who led his country to the semi-finals of the 2020 European Championship before being beaten by England, has steadied the ship by guiding the side to third in the league and building on that with this impressive away victory.

The visitors scored with both of their shots on target, while at the other end, Flekken was in inspired form, making seven saves to preserve a thoroughly deserved clean sheet.

This was just Leverkusen's second win from five games in the Champions League this seaso,n but an important one, lifting them up to 13th in the table, which would see them progress to the play-off stage.