The third-tier hosts knocked Reims out of the competition on penalties to make it this far, while Julien Stephan's side also needed the lottery of a 12-yard shootout to eliminate Marseille.
Match preview
As well as their attempts to return to Ligue 2 at the first time of asking - having been relegated to the Championnat National at the end of last season owing to their critical financial situation - Sochaux remain in contention to add a third Coupe de France honour to their modest cabinet.
Jura Sud and Geispolsheim both fell to Les Lionceaux's superiority before they came from behind to dump Lorient out in the round of 64 - their reward for which was another glamour tie against top-tier opposition in the shape of Will Still's Reims.
It took an 82nd-minute equaliser from Emmanuel Agbadou for Reims to avoid being dumped out in normal time, as the Ligue 1 outfit forced penalties by virtue of a 2-2 draw, but Teddy Teuma and Joseph Okumu fluffed their lines to send Sochaux through to the last 16 for the first time since 2017-18.
Tuesday's hosts swept aside the competition to lift the Coupe de France trophy as recently as 2007 - beating Marseille on penalties in the final 17 years ago - but they head into Tuesday's game having seen their six-game winning sequence come to an end in Friday's league affair with Red Star.
On that occasion, Oswald Tanchot's men threw away a two-goal lead given to them by right-back Julien Dacosta to share the spoils with the league leaders - a major opportunity missed indeed - and their opponents' recent exploits do not make for positive reading for the Lionceaux faithful either.
Rennes are by no means immune to a Coupe de France giant killing, but Julien Stephan's side have been building up a head of steam over the Christmas and New Year period and travel to their third-tier foes on the back of six straight wins in all tournaments.
Those successes include knockout beatings of Guingamp and most recently Marseille, whom they held to a 1-1 draw at Roazhon Park before a nail-biting 18-attempt penalty shootout, where all nine of Rennes' strikes found the mark, but Samuel Gigot would be the guilty party to come up with Les Olympiens' only miss.
By holding their nerve from the 12-yard mark, Les Rouges et Noir - who won their third and most recent Coupe de France crown during Stephan's first glittering reign in 2018-19 - have progressed to the last 16 for the first time since the 2019-20 season, when their journey ended in the final four.
Since sending Marseille packing, Rennes' Ligue 1 renaissance has gathered pace with successive beatings of Lyon (3-2) and Montpellier HSC (2-1), and from their last three away games in domestic football, Stephan's men have chalked up an eye-catching eight goals.
Frequent foes in years gone by, Sochaux and Rennes will be renewing hostilities for the first time since the 2013-14 season - when Les Lionceaux clinched a pair of 2-1 victories - and Les Rouges et Noir have not got the better of their upcoming hosts for over 11 years.
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Team News
Sochaux's newly-assembled squad are in relatively good health at the minute, although midfielder Mouhamadou Drammeh is working his way back from a foot fracture and will sit out Tuesday's tie.
Only two players who started the last-32 win over Reims failed to hold their places for the meeting with Red Star, as Kevin Zohi replaced N'Dri Koffi at the tip of the attack, while Maxime Bastian got the nod at left-back over Dalangunypole Gomis.
Bastian followed another ex-Strasbourg player in Dimitri Lienard to the Stade Auguste-Bonal in January, although the latter is likely to settle for substitute minutes once again.
As for Rennes, only Fabian Rieder (foot) and Jeanuel Belocian (knee) are expected to miss the last-16 clash with injury, and neither man should make their comebacks before March rolls around.
Winger Desire Doue only lasted until half time in the meeting with Montpellier, so Amine Gouiri may force his way into the XI in a tactical alteration from Stephan, who should also recall Gauthier Gallon in between the posts.
Sochaux possible starting lineup:
Patouillet; Dacosta, Vitelli, Fontaine, Bastian; Pereira de Sa, Viltard; Fatar, Michel, Daho; Koffi
Rennes possible starting lineup:
Gallon; G. Doue, Wooh, Seidu, Truffert; Blas, Matusiwa, Le Fee, Gouiri; Terrier, Kalimuendo
We say: Sochaux 1-3 Rennes
If their beatings of Reims and Lorient are anything to go by, a rejuvenated Sochaux are not to be underestimated, and a few alterations on the visitors' end could give rise to an exciting last-16 affair.