The Blues travel to the County Ground for their third round Capital One clash and the Spaniard is set to drafted in after being axed for the weekend's 1-0 Barclays Premier League win over Fulham.
David Luiz, who was also dropped from Mourinho's squad on Saturday, is expected to force his way back into the starting XI too, while Fernando Torres could also feature from the outset.
In the cold: Juan Mata was forced to watch
Chelsea's win over Fulham at the weekend alongside David Luiz (behind
manager Jose Mourinho) from the stands
Mata's exclusion has proved to be the real point of debate, however, with may confused as to the 25-year-old star's omission.
Last season he was voted Chelsea's player of the season but since Portuguese boss Mourinho returned to Stamford Bridge he has been overlooked with Oscar getting the nod as his No 10.
Mourinho insisted on Saturday that he wants Mata and Oscar to line-up together but warned the Spaniard but must adapt his game as he 'doesn't work hard enough'.
He said: 'I think the evolution of the team and the way I want to play, Mata and Oscar can play together. I want that.
What's the Mata: Mourinho insists the Spaniard playmaker needs to adapt his playing style
Talking point: A Chelsea fan holds up a sign saying Mata belongs on the field not on the bench
'For that, Juan has to work and has to adapt to a certain way of playing because I'm not ready to change Oscar's position.
'Oscar as a number 10 is a player who gives us creativity, but at the same time, when we want to press up, Oscar is a runner and he is a player capable of pressing. Even when we play against a double pivot, like Sidwell and Parker for example, who have a distance of 15-20 metres between them.
'We have our ideas and we stick with our ideas'.
Mourinho's stance has courted criticism, however, with former Blues manager Avram Grant questioning the marginalisation of Mata.
Capital Juan chance: Mata will now look to impress Mourinho against Swindon on Tuesday night
'I personally don’t understand [why he left Mata out],' said Grant said.
'But in this position Chelsea have so many players, so if Oscar, Eden Hazard, or Willian are out, people will ask why they are out of the squad or team.'
Mata, who scored 20 goals last season and joined Chelsea for £23.5million from Valencia in 2011, was linked with an exit in the summer window but will bid to convince Mourinho against Swindon to stick by him.
