Manager Jose Mourinho has told Mata, who has made two starts this term after being near ever-present in his first two seasons at Chelsea, to prove his worth at the County Ground.
Right-back Cesar Azpilicueta, left-back Ryan Bertrand and midfielder Michael Essien are in line to feature for a Chelsea side with no fitness concerns.
Tottenham manager Andre Villas-Boas will ring the changes for Tuesday's Capital One Cup clash at Aston Villa.
The Spurs boss has expressed his frustration that the fixture takes place just two days after their Premier League win in Cardiff, and very few who featured in south Wales are likely to start at Villa Park.
The likes of Brad Friedel, Erik Lamela, Lewis Holtby, Sandro and Vlad Chiriches could all start, but Jermain Defoe is a doubt due to a groin strain.
Aston Villa boss Paul Lambert is set to make sweeping changes to his line-up.
Gabriel Agbonlahor and Antonio Luna are almost certain to sit out after returning from injury problems in Saturday's Barclays Premier League win at Norwich.
Jed Steer is set to replace Brad Guzan in goal and there are also expected to be starting places for the likes of Nicklas Helenius and Yacouba Sylla.
Manchester City defender Micah Richards could make his first appearance of the season in the Capital One Cup third-round tie against Wigan.
Richards has missed the start of the season with hamstring trouble but was an unused substitute in the weekend derby win against Manchester United.
Midfielder Jack Rodwell missed that game with a knock and could be doubtful while playmaker David Silva (thigh) and defender Gael Clichy (thigh) continue to be assessed. Changes are probable with the likes of Joleon Lescott, James Milner and Stevan Jovetic pushing for places.
Cardiff boss Malky Mackay is set to make a host of changes to his side for the Capital One Cup trip to West Ham.
The likes of Nicky Maynard, Mark Hudson, Joe Lewis, Don Cowie, Jordan Mutch and Craig Noone are all be in contention to feature at Upton Park, while Mackay could opt to hand new signing Peter Odemwingie a first start.
Andreas Cornelius is unlikely to be involved as the striker works to recover from the ankle injury picked up in the last round at Accrington.
West Ham are without suspended midfielder Mark Noble for the third-round tie.
Noble picked up a one-match ban after being sent off for two bookable offences in Saturday's loss to Everton.
Midfielder Joe Cole (hamstring) and winger Stewart Downing (leg) are improving but not yet ready while manager Sam Allardyce has suggested it is still too soon for striker Mladen Petric to start. Striker Andy Carroll (heel) and midfielder Alou Diarra (knee) are out.
Dimitar Berbatov, Aaron Hughes and Bryan Ruiz could all return for Fulham's Capital One Cup third-round clash with Everton.
Berbatov (hamstring), Hughes (thigh) and Ruiz (ankle) missed Saturday's 2-0 loss at Chelsea but could improve Martin Jol's options in the all-Premier League clash as the Cottagers bid to end a six-match winless run at home.
Matthew Briggs (hernia) and first-choice goalkeeper Maarten Stekelenburg (shoulder) are out.
Midfielder Darron Gibson could be set for his first appearance of the season for Everton.
The Republic of Ireland international has been out with a knee injury but manager Roberto Martinez now considers him fully fit.
Changes are expected from the side which beat West Ham at the weekend but midfielder Steven Pienaar, Antolin Alcaraz (both hamstring) and Leon Osman (groin) will not be risked.