Liam Rosenior hailed the fighting spirit Chelsea showed to come from behind and stay in the contest with Arsenal in their EFL Cup semi-final first-leg tie.

Arsenal emerged 3-2 winners at Stamford Bridge on Wednesday, despite Alejandro Garnacho's second-half brace.

Ben White, Viktor Gyokeres and Martin Zubimendi all got on the scoresheet for the Gunners, who take a slender one-goal advantage into the second leg at Emirates Stadium on February 3.

Rosenior became the seventh consecutive Chelsea boss to fail to win their first home game in charge (D5 L2), with Maurizio Sarri the last to win on his bow at Stamford Bridge in August 2018.

But the 41-year-old remained optimistic about Chelsea's prospects of reaching the final of the EFL Cup after the determination they showed in the second half.

"It's half-time [in the tie]. I was very happy with the engagement, the commitment of the players," Rosenior told beIN Sports.

"They gave everything. It was every open game. Disappointed to concede from a corner. Disappointed with the third goal as well, because we were right back in the game, and we were on top at that moment.

"We switched off from a restart from a central free-kick, but I can't fault the players. We've had illness in the squad, we've picked up a few knocks this week, but what the squad has shown is that they are willing to run and fight for each other."

Robert Sanchez was left in no man's land for Arsenal's opener from a corner, and he also let White's centre squirm under his hands, allowing Gyokeres to tap in their second.

However, he also made three saves, with Rosenior highlighting one in particular that could prove key for Chelsea in the second leg.

"Rob's a very good goalkeeper," he said of Sanchez.

"He made an outstanding save at 3-1 to keep us in the tie, so for me, loads of things to improve, but the overall attitude of the team I liked. Hopefully, we get a few bodies back for Brentford on Saturday."

Garnacho, who scored with both of his shots on goal after his 53rd-minute introduction, also scored twice off the bench to secure Chelsea's win over Cardiff City in the last eight.

He became the first Premier League player to score twice in both a quarter-final and a semi-final in the same EFL Cup campaign since Edin Dzeko for Manchester City in 2013-14.

Overall, he has netted five goals as a substitute in all competitions this term, more than any other player in the English top-flight.

"I said he would be important off the bench, and he proved that," Rosenior added on Garnacho.

"I've got an outstanding squad. What I need them to do is be engaged, whether they start the game or whether they come off the bench. Garna showed his quality.

"I think Pedro Neto was magnificent. Estevao was outstanding as well. We need to make sure if we perform well individually, we don't concede as many goals."