Liam Rosenior's new Chelsea tactic that exposed them to Arsenal's attack

Liam Rosenior wanted to show his football to Stamford Bridge for the first time, and that included playing from the back whenever they had a goal-kick, but Arsenal were the worst opponents he could have encountered for that introduction.

They are one of the best pressing sides in the Premier League, if not the best, and Mikel Arteta's visitors were relentless here.

They suffocated Robert Sanchez and Co whenever they tried to play those pretty passes to one another, often forcing a mistake to be made.

Chelsea's fans were very vocal in letting their frustrations known.

This was not, with all due respect, Burnley they were trying to pass around. It was Arsenal, and that was a problem, as Bukayo Saka, Viktor Gyokeres, Leandro Trossard and Co represented the Red Arrows.

Those who regularly attend games at Stamford Bridge were already fed up with this type of approach under Enzo Maresca, so seeing it struggle here was never going to go down well.

But Rosenior is married to this idea, and will hope, in time, they see its benefits live.

Chelsea give themselves hope despite absentees

No Reece James. No Cole Palmer. No Malo Gusto. No Liam Delap. No Jamie Gittens.

Sometimes, this would be where we write 'no problem', if the side in question somehow managed to overcome the odds without their crocked cast.

Chelsea lost, but they have hope, slim as that may be.

Two Pedro Neto crosses and two Alejandro Garnacho goals represented lifelines, leaving them in this semi-final tie – just – as Rosenior hopes he will have some of his big names returning for the second leg.

James was missing after taking a whack to the hip, but it is only thought to be a minor issue. Delap and Gittens were ill. Gusto's issue is unknown. Palmer's groin is still proving problematic. Moises Caicedo was also suspended here but he will be back at the weekend and for the second leg.

Rosenior's early tweaks

Another tactical idea that Rosenior had was to go man-to-man out of possession with Wesley Fofana told to follow Martin Odegaard wherever he went.

The issue was, however, that left space at the back for Arsenal to attack. In the 15th minute, for example, it led to a chance for Gyokeres. Chelsea managed to defend the subsequent corner.

Meanwhile, Chelsea's set-piece coach Bernardo Cueva now has a seat down at the front of the technical area, rather than at the very back. Already, he is looking much closer to Rosenior than he ever was with his predecessor, Maresca.

Guiu's late call-up

Marc Guiu looked somewhat lost while leading the line, though it was only around 4.30pm that he discovered he would be starting. Delap was supposed to start, but he reported that he felt too ill to play only a few hours before kick-off.

Dissent continues to be a problem

It would not be a Chelsea game without someone being booked for dissent. Here it was the turn of Estevao Willian, the usually mild-mannered 18-year-old showing his angry side.