The last time Calum Chambers was seen on a football pitch, Arsenal were spiralling towards an early-season crisis and Mikel Arteta was under considerable pressure in the dugout. That was in their 5-0 thrashing by Manchester City in August, and Chambers has since had to watch from the sidelines as his team-mates have rediscovered their form.

How satisfying it must have been, then, for Chambers to score Arsenal’s opening goal with his first touch of the ball in this League Cup meeting with Leeds United. Introduced as a substitute just a few seconds earlier, he surprised the visitors by materialising at the back post and sending Arsenal on their way to another victory.

The mood around this team, and indeed Arteta, has transformed completely since those dark days in August, with Arsenal now unbeaten in eight matches in all competitions. They were more clinical than Leeds at the Emirates, where Eddie Nketiah added a second against a Marcelo Bielsa team which continues to look off the pace.

A run of one win in nine league matches is a source of considerable concern for Leeds, who played well in the first half here but were too open for too much of the second period. Arsenal capitalised, despite their weakened team, and the frustration was etched all over Bielsa’s face on the touchline.

For Arsenal this was a night to maintain the momentum they have built in recent weeks, and for some of the fringe players to make a point to their manager. Chambers certainly did that, changing the game after replacing the unwell Ben White at the start of the second half, and there was a clear sense of personal and collective joy as he celebrated his goal with his coaches and team-mates.

“I am so happy for Calum,” said Arteta. “He totally deserved it. You see the reaction of his team-mates, who spend time with him every single day. It was genuine emotion for him because it has been tough for him and they like him as a person. There were three different coaches and a player who told him he was going to score.”

There would have been similar relief for Nketiah, the other goalscorer, as he fights for more minutes following the breakdown of his move to Crystal Palace this summer. Nketiah’s contract expires at the end of this season and Arteta said he wants the striker to stay at the club. “I have full belief that he is going to be a top, top player and hopefully at Arsenal”, said the Arsenal manager.

Arsenal had missed a handful of first-half opportunities before the goals but on the overall balance of play it was Leeds who created the better openings before the break. Bielsa’s side had plenty of space on the counter-attack, where Daniel James and Jack Harrison showed their pace, and both wingers tested Bernd Leno between the Arsenal posts after corners had only been half-cleared.

If James had been more aware of the overlapping run of Rodrigo Moreno, Leeds might easily have been ahead by the half-time whistle. They also threatened through Tyler Roberts and generally looked a more cohesive unit, which was perhaps to be expected given that Bielsa only made four changes to his side.

A knock to White presented Chambers with his unexpected opportunity shortly after half-time, and within seconds he had scored the opener. Emile Smith Rowe’s corner reached the back post, where Nicolas Pepe headed it back across the box. There was Chambers, lurking like an old-school poacher and powering his header over the line.

A few minutes later it was two, as Liam Cooper’s header left Meslier short and allowed Nketiah, who once had a loan spell at Leeds, to score a simple tap-in. The Arsenal striker almost made a mess of it, stumbling as he struck the ball, but his finish just about squirmed over the line.

Match details

Arsenal (4-2-3-1): Leno 7; Cedric 6, White 7 (Chambers 55), Holding 7 (Tavares 76), Kolasinac 6; Elneny 6 (Lokonga 72), Maitland-Niles 7; Pepe 6 Smith Rowe 7 (Lacazette 72), Martinelli 7; Nketiah 7
Subs: Ramsdale (g), Partey, Saka, Balogun, Oulad M’Hand Booked: Cedric

Leeds (4-1-4-1): Meslier; Drameh, Llorente 6 (Cooper 59), Struijk, Dallas; Phillips; Harrison, Forshaw 6 (Klich 45), Roberts 5 (Gelhardt 53), James (Summerville 70); Rodrigo (Greenwood 70)
Subs: Klaesson (g), Hjelde, Cresswell, McKinstry Booked: Roberts

Referee: Andre Marriner (West Midlands)

Arsenal 2:0 Leeds

Not a spectacular game by any measure but Arsenal get the job done, weathering first-half pressure from Leeds before getting the breakthrough from sub Chambers just 23 seconds after coming on and then fellow forgotten man – and ex Leeds player – Nketiah made sure with a close range finish.