The sixth-tier side progressed through the preliminary stage to set up a dream first-round tie against a La Liga team.
Match preview
San Pedro are preparing to compete in the main draw of the Copa del Rey for the first time since the 1994-95 competition.
The sixth-tier club qualified for the preliminary round via their fourth-place finish in last season's División de Honor - a league in the autonomous region of Andalusia.
San Pedro negotiated a preliminary round clash against fellow sixth-tier side Ceuta 6 de Junio earlier this month, producing a free-scoring display to record a 4-2 home win to seal their place in the first round.
They may have followed that win with a league defeat against Cuevas, but they bounced back to ease to a 4-0 victory in Sunday's home clash with Casabermeja.
San Pedro have now won three of their four home games this season, and they will attempt to make home advantage count as they look to pull off a major shock in the Copa del Rey.
Celta have found wins hard to come by in recent weeks, having won just one of their previous six matches (D1, L4).
They began that period of results with consecutive defeats against Athletic Bilbao and Atletico Madrid, before they drew with Girona and beat Las Palmas with nine men.
Unfortunately for Celta, they have been unable to take anything from their last two La Liga matches, losing 2-1 in their home clash with Real Madrid before falling to a heavy 3-0 defeat to Leganes in Sunday's away meeting.
After shipping three second-half goals at Butarque, Celta have now conceded at least three times in all four of their La Liga away defeats this season.
Despite their struggles on the road, the Galician outfit will be the overwhelming favourites for Wednesday's cup tie, especially as they have not suffered a first-round elimination since 1983-84.
UD San Pedro (Copa del Rey):
UD San Pedro form (all competitions):
Celta Vigo form (all competitions):
L
L
D
W
L
L
Team News
San Pedro boss Miguel Angel Berlanga is set to name a similar side to the one that started the preliminary round tie against Cueta 6 Junio, with Adrian Silva, Pedro Paulo, Fran Gonzalez and Steven Restrepo set to feature in the backline.
Experienced striker Alejandro Corbacho could be given the thankless task of leading the line against La Liga opposition.
As for Celta, Jailson is expected to be out until December after he sustained an adductor injury in training last week.
Midfielder Luca de la Torre is also set to miss Wednesday's cup clash as he continues to work his way back from an ankle issue.
Celta head coach Claudio Giraldez is poised to make wholesale changes, with Ivan Villar, Javi Rodriguez, Fran Beltran, and Anastasios Douvikas among those who could come into the side for the first-round tie.
UD San Pedro possible starting lineup:
Tudela; Silva, Paulo, F. Gonzalez, Restrepo; Carmona, Chino, M. Gonzalez, Pepe, Oliva; Corbacho
Celta Vigo possible starting lineup:
Villar; Manquillo, C. Rodriguez, Dominguez; Carreira, D. Rodriguez, Beltran, Ristic; Gonzalez, Cervi, Douvikas
We say: UD San Pedro 0-4 Celta Vigo
San Pedro will be looking forward to a dream tie against a La Liga side, but while it will be an unforgettable day for the hosts, we believe they will fall to a heavy defeat even if Celta decide to make wholesale changes for the cup clash.