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Peterborough also have a relatively new manager in the hot seat.

Robbie Savage, heard of him? The former Birmingham midfielder, Match of the Day pundit and Macclesfield boss took over a Posh side who had collected just one point from their opening seven league games.

Savage has started to turn things around with a first-match win over Leicester, but two points from their last three games mean Peterborough aren't out of the bottom four, yet.

A first win at Valley Parade in nine years tonight though could be the confidence boost Posh needs.

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Bradford may be in the fourth round, but their manager Michael Duff is leading them in this competition for the very first time.

Their previous cup wins, against Rochdale, Burnley and Leyton Orient, all came under Graham Alexander who took over at Preston last month.

Bradford haven't conceded a goal yet under their new manager and are currently on an 11-match unbeaten run!

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At least one League One club will be in the quarters with Bradford City hosting Peterbourough United in tonight's earlier game.

The Bantams are flying high in the third tier, up in third, and haven't lost since September 1st (2-1 against Cambridge, thanks for asking).

Peterborough meanwhile are in the bottom three with just two league wins all season.

The Posh really are up against it tonight. The two clubs met earlier in the season too, in the league on the opening day, with Bradford winning 2-0.

Right, two matches to focus on tonight. One starts slightly sooner, so we'll start our build up there.

BBC Radio 5 Live

Oh, and did you also know we're on BBC Radio 5 Live tonight?

Click the play icon at the top of this page to hear Kelly Somers and the team build up to full live commentary of Fleetwood vs Arsenal.

OK, what do we think to those teams? Arsenal fans, a second-choice keeper making a surprise appearance in a Carabao Cup match, where have we heard that one before?

Have your say on all of tonight's action by getting in touch using the usual method.

Michael Duff makes four changes to his Bradford City side that drew 0-0 with Oxford United in League One at the weekend.

Reece Welch, Macaulay Gillesphey, Jake Beesley and Bobby Pointon all come into the starting XI.

Bradford XI: McCracken, Pennington, Welch, Gillesphey, O'Keeffe, Sarcevic, Connolly, Touray, Lapslie, Pointon, Beesley

Subs: Baldwin, Cartwright, Dawson, Jackson, Matthews, Morgan, Phillips, Pratt, Swan

It's four changes for the Peterborough XI too after the 1-1 draw at Bromley in League One.

Josh Feeney, Brandon Khela, Vernon Masara and Danny Ormerod are given the nod by Robbie Savage.

Peterborough XI: Bass, Johnston, Feeney, Mills, Ashfield, Khela, Edwards, Williams, Masara, Ormerod

Subs: Andeng-Ndi, Dornelly, Frith, Garbett, Jones, Kelly, Shofowoke, Sykut, Weir

Matt Lawlor makes two changes to his Fleetwood side that fell to a 2-1 defeat at Exeter City in League Two at the weekend.

Rhys Bennett and Aaron Loupalo-Bi come in for Lewis McCann and Ronan Coughlan.

Andy Cannon returns from injury to make the bench, while Finley Potter starts despite suffering a nasty cut above his eye against Exeter.

Fleetwood XI: Lynch, Rooney, Bennett, Potter, Haughey, McLean, Neal, Helm, Batty, Evans, Loupalo-Bi.

Subs: Pradic, Andrew, Cannon, Davies, Thomas, Murphy, Coughlan, Robertson, Cirino.

Only Myles Lewis-Skelly and Viktor Gyokeres keep their place in Arsenal's starting XI from their 2-0 win against Everton on Saturday.

Illan Meslier makes his debut in goal after joining in the summer, while 18-year-old Northern Ireland international Ceadach O'Neill makes his first senior appearance for the club.

Mikel Arteta also starts teenagers Max Dowman and Marli Salmon, who both featured in the third-round win over Ipswich.

Arsenal XI: Meslier, Timber, Salmon, Mosquera, Hincapie, Zubimendi, Lewis-Skelly, Dowman, O'Neill, Havertz, Gyokeres.

Subs: Arrizabalaga, White, Odegaard, Eze, Konsa, Guimaraes, Harriman-Annous, Washington, Hashi.

Time for some team news....

Two games for you tonight, then five on Wednesday and one on Thursday.

Tuesday

Bradford v Peterborough (19:45 GMT)

Fleetwood v Arsenal (20:00 GMT)

Wednesday

Manchester City v Brighton (19:30 GMT)

Bournemouth v Aston Villa (19:45 GMT)

Fulham v Crystal Palace (19:45 GMT)

Sunderland v Brentford (19:45 GMT)

Liverpool v Chelsea (20:00 GMT)

Thursday

Everton v Newcastle (19:45 GMT)

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The last 16.

This is where clubs start to get serious.

Win this one and then, well, it's the quarters. You're only two rounds from Wembley.

Sure the early rounds were for squad rotation, but now it's time to lock in. There are trophies to be won.