Life is a rollercoaster ride at Stamford Bridge.

After stumbling to a first defeat of the season with a lacklustre performance at Newcastle there was an effortless glide past the Champions League group stage… coupled with news that the talisman of Chelsea’s most feared opponents is crocked.

Sergio Aguero’s knee injury means Manchester City’s free-scoring front man will be out of action for at least a month.

In fact, he’s expected to return to the fray on the last day of January, when the Sky Blues face the Blues in a Premier League cruncher at the Bridge.

That game has already been snaffled by Sky and shuffled back to a 5.30pm kick-off.

Aguero’s absence gives Chelsea hope of increasing a gap which has been gradually narrowing at the top of the table; a gap reduced to three points by defeat at St James’ Park.

But it will require a firmer focus, and a better plan B for Jose Mourinho’s first-choice players, thwarted by determined defending at both Sunderland and Newcastle.

On Wednesday night, under the floodlights, Chelsea breezed to a 3-1 win over Sporting Lisbon, with John Obi Mikel an unlikely scorer alongside Andre Schurrle and Cesc Fabregas.

The Blues had already qualified for the last 16 of the Champions League, but this victory steadied the ship, gave some less regular names a chance to shine and provided a terrific 10-minute cameo debut for Reuben Loftus-Cheek, a midfield prospect from the club’s academy.

In Monday’s draw Chelsea could come up against PSG, Shakhtar Donetsk, Basel, Juve or Bayer Leverkusen.

But first there’s the little matter of Hull City visiting the Bridge this afternoon as the matches start coming thick and fast.

Steve Bruce’s side are in the bottom three, but his teams traditionally give Chelsea a tough ride.

Then, on Tuesday, comes the jaunt to Derby County for a League Cup clash which will need guts as well as skill.