The Villa manager, who has now lost his first two competitive games since taking charge of the club, saw the hangover from relegation out of the Premier League continue as they were deservedly knocked out by the Hatters.
Villa dominated the opening 20 minutes, hitting the frame of the goal twice and taking the lead through Jordan Ayew’s 13th-minute goal. But Luton levelled nine minutes before the interval through Jake Gray before Cameron McGeehan put Luton ahead early in the second half and Jores Okore comically put through his own net in the 66th minute.
Di Matteo said: “We went deservedly ahead, and then let Luton back into the game as second half they dominated us and we looked disjointed as a team.
“It wasn’t a team performance, also difficult to explain from first half to second half how we changed so much.”
Villa are without a win in any competition since February 6 and Di Matteo admitted the team need to toughen up mentally.
The former Chelsea manager added: “Certainly there’s some fragility there, because after we conceded the equaliser you could see they were a little bit nervous, but I didn’t expect in the second half we would play like that.
“We have to work together as a team and try to get a win and grow their confidence. We let ourselves down and lose games, so we probably have to go back to basics, defend well, defend our box and take our chances. We did create chances but we need to make sure we don’t concede so easily.”
Luton manager Nathan Jones was thrilled with his players. He said: “I’m very, very proud, I thought they were excellent.
“We started very slowly but once we realised we could affect a football game against Aston Villa, I thought we were excellent, especially second half.
“They showed they could competed first half but second half they showed a real desire to win a football match and I thought we were excellent.
“We had a little bit of fortune at times, they hit the woodwork, but it was slim margins.”
Luton Town were rewarded with a home tie against Leeds United, who defeated Fleetwood Town 5-4 on penalties. QPR, the night’s other victors from the spot when they defeated Swindon after a 2-2 draw, got a home game against Rochdale.
Burton Albion got themselves a plum draw for the second round of the League Cup, newly branded as the EFL Cup from this season, when they were handed a home game against Liverpool.
Albion, managed by an Anfield old boy Nigel Clough, defeated Bury 3-2 after extra time and started their first ever season in the Championship only on Saturday against another of his former clubs, Nottingham Forest, and lost it 4-3.
Liverpool, eight times winners of the League Cup, the last of them in 2012 under Kenny Dalglish, got to the final last year and lost it on penalties to Manchester City after a 1-1 draw.
Chelsea will host one of the Bristol clubs at Stamford Bridge – depending on the winner of the Bristol Rovers v Cardiff City game on Thursday, as the draw was seeded. Newcastle United will take on Cheltenham Town, who provided the upset of Tuesday with a 1-0 home win over Charlton. Everton will face Yeovil Town for the first time in a competitive fixture and Sunderland get to face lowly Shrewsbury Town, which may provoke unhappy memories for the new manager David Moyes, who lost a third-round FA Cup tie against them with Everton 13 years ago.
Millwall face Nottingham Forest, Accrington play Burnley in a Lancashire derby and Norwich City, the 1985 winners when it was called the Milk Cup, will face Coventry City, Crystal Palace will host Blackpool and Watford will take on Gillingham at Vicarage Road.
Full draw: QPR v Rochdale
Scunthorpe v Cardiff/Bristol City
Watford v Gillingham
Peterborough v Swansea
Everton v Yeovil
Millwall v Nottm Forest
Sunderland v Shrewsbury
Luton v Leeds
Chelsea v Bristol Rovers/Bristol City
Burton v Liverpool
Blackburn v Crewe
Accrington v Burnley
Crystal Palace v Blackpool
Morecambe v Bournemouth
Preston v Oldham
Oxford v Brighton
Reading v MK Dons
Fulham v Middlesbrough
Newcastle v Cheltenham
Exeter v Hull
Derby v Carlisle
Northampton v West Brom
Wolves v Cambridge
Stevenage v Stoke
Norwich v Coventry
Ties to be played week commencing August 22
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