After their home victory over The New Saints sparked a revival in Serie A, the Viola now face opponents that were thumped 6-2 on the opening matchday.
Match preview
Having reached the final in both of the past two years, Fiorentina almost missed out on another Conference League campaign this term, as it took a penalty shootout to edge past Puskas Academy in the playoffs.
The Tuscan side then toiled before beating Cymru Premier club TNS 2-0 at Stadio Franchi in their league-phase opener, with Yacine Adli and Moise Kean both netting midway through the second half.
Up to that point, Fiorentina's league form had been sub-par after Raffaele Palladino took the reins from former boss Vincenzo Italiano - they had failed to win any of their first four Serie A fixtures for the only time in five years - but distinct signs of progress have since emerged.
The Viola posted back-to-back wins just before the international break - over two very different opponents, TNS and then AC Milan - with the latter featuring two David de Gea penalty saves and a goal from Milan-owned Adli against his parent club.
Now, fresh from a 6-0 thumping of 10-man Lecce at Via del Mare, they will head for Switzerland occupying fifth place in the Serie A standings, just six points shy of top spot.
In stark contrast to Fiorentina's recent form, St Gallen slumped to a 6-2 defeat against Cercle Brugge in their Conference League opener, with second-half strikes from Kevin Csoboth and Felix Mambimbi offering scant consolation.
That setback left them 35th in the 36-team table, and while just one game has been played, there are only six league fixtures in UEFA's third-tier tournament, compared to eight in both the Champions League and Europa League.
Switzerland's oldest club came through qualifying to reach this phase of the competition, unexpectedly eliminating Trabzonspor along the way, but they already have plenty of work to do in order to make the knockout rounds.
Following a 2-1 loss to Basel at the weekend, Enrico Maassen's side are winless in four games, but they still sit sixth in the Swiss Super League standings.
On home soil this season, St Gallen went undefeated through three Conference League qualifiers, so they will hope to use that advantage to defy the odds on Thursday.
St Gallen Conference League form:
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St Gallen form (all competitions):
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Fiorentina Conference League form:
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Fiorentina form (all competitions):
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Team News
Though Raffaele Palladino named the same lineup for both of Fiorentina's recent league wins, he is set to make sweeping changes in midweek, with one eye on Sunday's game against Roma.
Palladino will be back in the dugout after serving a Serie A suspension, while defensive trio Luca Ranieri, Pietro Comuzzo and Lucas Martinez Quarta are available following UEFA bans.
Iceland striker Albert Gudmundsson pulled up with a hamstring injury last weekend and must join Marin Pongracic on the sidelines; star players such as Moise Kean are set to be rested.
Meanwhile, St Gallen's leading league scorer Willem Geubbels found the net against Basel last time out and should lead their attack once again.
Providing support from behind, former Switzerland Under-21 captain Bastien Toma has four assists to his name this season, plus two goals in the Conference League qualifiers.
Chadrac Akolo, Betim Fazliji, Gregory Karlen and Ghana centre-back Stephan Ambrosius are all consigned to the hosts' treatment room.
St Gallen possible starting lineup:
Ati-Zigi; Faber, Stanic, Fallci, Yannick; Stevanovic, Quintilla, Gortler; Toma; Mambimbi, Guebbels
Fiorentina possible starting lineup:
Terracciano; Kayode, Moreno, Martinez Quarta, Biraghi; Richardson, Adli; Ikone, Beltran, Sottil; Kouame
We say: St Gallen 1-3 Fiorentina
Fiorentina may not always travel well, but a squad that has safely negotiated their way to the final in consecutive campaigns should have enough nous to see off St Gallen.