Manchester United will miss out on £50m if they fail to beat Ajax in the Europa League final on 24 May.
The game in Stockholm is their only remaining chance of reaching next season's Champions League.
Failure to qualify for Europe's flagship club competition for a second successive season would trigger a £21m penalty clause in their 10-year, £750m sponsorship deal with Adidas.
United also expect to earn up to £30m more by being in the Champions League.
The Old Trafford club's financial officer Cliff Baty said: "For us the bigger prize is Adidas and Champions League.