The Millers are aiming to avoid an instant return to League One after promotion, while the Swans will hope to improve on last season's 15th-placed finish.
Match preview
Despite a loss of form towards the end of last season, Rotherham managed to cling onto an automatic promotion spot, ultimately finishing a point ahead of third-placed Milton Keynes Dons in League One.
The Yorkshire-based side are in a serious yo-yo cycle under manager Paul Warne, with their record since he took over the club in 2016 reading: relegated from the Championship, promoted from League One, relegated from the Championship, promoted from League One, relegated from the Championship, promoted from League One.
The 49-year-old will be desperate to put that run to an end this season by avoiding relegation, but the scale of the task awaiting him and his players is best summed up by the fact their star strikers of the past four seasons, Michael Smith and Freddie Ladapo, have both opted to drop back down a level to Sheffield Wednesday and Ipswich Town respectively.
It's clearly a huge ask for the incoming Tom Eaves and Conor Washington to replace the departed duo's goal threat at this level. Both will provide the industriousness Warne demands of his players, but neither have ever bagged double figures in a Championship campaign.
With all that being said, Rotherham have gone seven games unbeaten in pre-season, and Warne will be hopeful of there being three teams less competitive than his side this season. His players will undoubtedly always give their all under him, starting with a tough test against Swansea on Saturday.
Swansea, meanwhile, showed flashes of brilliance in Russell Martin's debut campaign after the former Norwich City defender's switch from the MK Dons dugout, but ultimately paid for a porous defence as they failed to mount a challenge for the play-offs.
Indeed, only five teams conceded more goals than them in the Championship last season, making it clear where Martin needs to focus on improvement in the coming campaign.
Harry Darling has joined for around £2m from his former club, with Nathan Wood also adding to Martin's options in the centre of defence. Fans' favourite Joe Allen should help the Welsh outfit keep hold of the ball in midfield to an even higher standard, too, after returning to his boyhood club on a free transfer from Stoke City.
Flynn Downes's industry in the middle of the park will be a significant loss after the 23-year-old departed for pastures new at West Ham for close to £10m, though, while Martin will be desperate to fend off any bids for strikers Joel Piroe and Michael Obafemi, who bagged 34 league goals between them last season.
Should they manage to keep the pair, and with another year of Martin's possession style ingrained in them, there are all the makings of a play-off push at the Liberty Stadium this season. Saturday's trip to Rotherham will provide a stern test of their ability to break down sides who by and large look to defend first and foremost.
Rotherham United pre-season form:
Swansea City pre-season form:
Team News
Rotherham may be without new recruit Jamie McCart after the former St Johnstone defender picked up a knock in last weekend's 2-1 friendly win at Crewe Alexandra.
Captain Richard Wood replaced him at half-time and the 37-year-old may receive a start with his experience likely to prove vital in the coming campaign.
Washington, who bagged 11 goals in each of the last two seasons for Charlton Athletic in League One, and Georgie Kelly are likely to combine in attack after both scored in the victory.
Swansea, meanwhile, are set to be without defender Ben Cabango and midfielder Liam Kelly due to ankle and Achilles' injuries respectively.
Nathan Wood and Darling should make their competitive debuts for the club in the defence, with Piroe and Obafemi putting any transfer rumours surrounding them aside to start up front.
Rotherham United possible starting lineup:
Johansson; Harding, Hall, R Wood; Kioso, Barlaser, Lindsay, Rathbone, Ferguson; Kelly, Washington
Swansea City possible starting lineup:
Fisher; Naughton, N Wood, Darling; Latibeaudiere, Fulton, Grimes, Sorinola; Paterson, Piroe, Obafemi
We say: Rotherham United 1-3 Swansea City
We expect a long, hard season for Rotherham at this level, starting with a tough test against free-scoring Swansea on Saturday.
Piroe and Obafemi are one of the division's stronger strike pairings, and they could enjoy themselves against the Millers' defence.