The Northerners, who are floating just three points above the relegation zone in Ligue 1, dominated throughout to set up a final clash with either holders Paris St Germain or Toulouse.
Yassine Benzia opened the scoring in the seventh minute from close range after a defensive blunder by goalkeeper Jerome Prior, starting an unlikely goal feast as Lille have the second worst attack in the French league.
Clement Chantome equalised shortly after the half hour with a shot from inside the box but the home side regained the lead when Lamine Sane netted an own goal.
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On the stroke of halftime, Adama Soumaoro made it 3-1 after latching onto Renato Civelli’s headed cross and Eric Bautheac wrapped it up in the 56th with a fourth while Sofiane Boufal added to Bordeaux’s woes with a fifth in injury time.
PSG, who won the last two editions of the competition, take on Toulouse at the Parc des Princes on Wednesday (2005 GMT). The final will be played at the Stade de France on April 23.
(Reporting by Julien Pretot, editing by Pritha Sarkar)
