This will be the first meeting between the two sides in over a decade, with Ruben Amorim's side picking up a hard-earned 1-0 victory when they faced off in Primeira Liga back in April 2012.
Match preview
Uniao de Leiria were denied successive wins in the Segunda Liga for the first time since November as they could only salvage a 1-1 draw with Porto 'B' when the sides met last Saturday.
Antonio Folha's men took the lead thanks to a 19th-minute strike from Abraham Marcus but 35-year-old defender Bura came up clutch for the hosts as he netted on the stroke of half time to force a share of the spoils.
Prior to that, Uniao de Leiria snapped their run of five consecutive league games without a win on January 19, when they scraped a 1-0 victory over Benfica 'B', courtesy of a second-half effort from Tiago Ferreira.
Vasco Costa's side, who are currently 13th in the Segunda Liga table, now turn their attention to the Taca de Portugal, where they have enjoyed a superb campaign, brushing aside Pedrogao, Academico Viseu, Malveira and Maritimo to reach the quarter-finals.
Having kicked off their cup quest with a 12-0 thrashing of Pedrogao on September 9, Uniao de Leiria picked up a 3-1 victory over Academico Viseu in the second round on October 21, four weeks before cruising to a 5-0 home victory over Malveira.
In the fifth round, they passed the Maritimo test with flying colours as they secured a 3-0 victory at the Estadio do Maritimo, with Jair da Silva, Valdir and Lucho Vega getting on the scoresheet to cap off a solid team performance.
Os Lis' toughest cup challenge awaits them on Wednesday as they take on a star-studded Sporting Lisbon side, who are unbeaten in each of their last six encounters, claiming four wins and two draws since a 1-0 loss in December 2009.
While Uniao de Leiria will be looking to end this run and cause arguably the biggest upset of the competition, they have struggled to get going at home, where they are without a win in four consecutive games, losing once and picking up three draws since December.
Like their midweek opponents, Sporting Lisbon have enjoyed an impressive run to the Taca de Portugal quarter-finals, scoring a staggering 15 goals and conceding just once in their three matches so far.
The Leoes kicked off their quest for an 18th cup title on October 21, when they picked up a 3-1 victory at Olivais e Moscavide, four weeks before returning home to thrash Dumiense 8-0 in the fourth round.
Sporting Lisbon made light work of Tondela in the fifth round as they thrashed the Gold and Greens 4-0 on January 9 courtesy of two goals each from Vitor Gyokeres and Portuguese forward Pedro Goncalves.
Since beating Porto on penalties in the final back in 2019, Amorim's side have not made it past the Taca de Portugal semi-finals, a run they will be looking to bring to an end this season and end their drought in the competition.
Sporting Lisbon have also put themselves on course for a first Primeira Liga title since 2021 as they sit second in the league table, two points behind first-placed Benfica, albeit with a game in hand.
The 19-time league champions picked up a statement win in their title challenge last time out as they steamrolled Casa Pia 8-0 when the two sides squared off at the Estadio Jose Alvalade.
Sporting Lisbon head into Wednesday's cup tie on a run of nine wins in their last 10 outings across all competitions, with a 1-0 defeat at the hands of Braga in the Taca da Liga semi-finals on January 23 being the exception.
Uniao de Leiria Taca de Portugal form:
Uniao de Leiria form (all competitions):
Sporting Lisbon Taca de Portugal form:
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Sporting Lisbon form (all competitions):
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Team News
We expect Costa to name his strongest possible XI, meaning that we should see a back three of Bura, Marco Baixinho and Vasco Oliveira, with Joao Oliveira between the sticks once again.
Pedro Empis, Diogo Amado, Leandro Silva and 23-year-old Valdir all started the fifth-round win over Maritimo on January 10 and should feature at the centre of the park on Wednesday.
At the attacking end of the pitch, we expect to see the front three of Vega, 26-year-old Da Silva and Honduras international Bryan Rochez, who has 11 goal involvements for club and country this season.
As for Sporting Lisbon, Amorim will be unable to call upon the services of Hidemasa Morita and Ousmane Diomande, who are currently away on international duties with Japan and Ivory Coast respectively.
On the injury front, Amorim will be unable to call upon the services of Dutch defender Jerry St. Juste, who has been ruled out since coming off injured against Gil Vicente on December 4.
Spanish defender Ivan Fresneda has been sidelined since suffering a shoulder injury against Rakow Czestochowa in November and the 19-year-old will also play no part in Wednesday's game.
With his brace against Casa Pia last time out, Gyokeres now has 18 goals and nine assists in 23 matches across all competitions and the Swedish striker will be one to keep an eye on.
Uniao de Leiria possible starting lineup:
J.Oliveira; Bura, Baixinho, V.Oliveira; Empis, Amado, Silva, Valdir; Vega, Da Silva, Rochez
Sporting Lisbon possible starting lineup:
Adan; Quaresma, Coates, Inacio; Esgaio, Hjulmand, Goncalves, Santos; Edwards, Trincao, Gyokeres
We say: Uniao de Leiria 0-4 Sporting Lisbon
Uniao de Leiria are in for a tough 90 minutes against a star-studded Sporting Lisbon side who are currently firing on all cylinders. Given the gulf in quality and experience between the two sides, we are backing Amorim's men to claim a comfortable victory at the Estadio Dr. Magalhaes Pessoa.