Roberts will make his competitive debut for Connacht when he starts on the left-wing. Swift returns to the side having missed the 15-8 victory over Glasgow at the weekend and will partner Andrew Browne in the second row.
Johnny O'Connor, introduced as a replacement against Glasgow having recovered from injury, which kept him out of the first two Magners League games of the season, will start in the back row.
Gavin Duffy, Keith Matthews and Ray Ofisa were not considered due to injuries picked up in the win over Glasgow.
Connacht coach Michael Bradley said this gave an opportunity to others to stake a claim.
"It gives the guys who did not start last week a chance to put down a marker ahead of the European Challenge Cup campaign," said Michael Bradley.
Connacht: F Carr; A Wynne, J Hearty, M Deane, M Roberts; A Dunne, F Murphy; J Lyne, A Flavin, R Morris; A Browne, M Swift; J Muldoon (C), J O'Connor, C Rigney.
Replacements: S Cronin, R Loughney, A Farley, M McCarthy, K Campbell, I Keatley, L Bibo.
Not considered due to injury: T Donnelly (shoulder), D Gannon (foot), C O'Loughlin (hip), D Riordan (hamstring), G Duffy (quad strain), K Matthews (shoulder) and R Ofisa (shoulder).
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