Spanish daily sport newspaper Marca has learned that the Irons are pursuing a deal for the current Real Betis forward. Scoring eight goals in 17 La Liga appearances before injury, the 22-year-old has an eye for goal.
With Los Verdiblancos only holding 50% of the rights to their striker - a joint ownership deal with Roma was struck in the 2016 transfer - Betis will hope to receive a hefty fee for the Paraguayan forward.
West Ham owners David Sullivan and David Gold haven't messed around this summer, tying down world renowned manager Manuel Pellegrini to a three-year deal. The business tycoons have also got their wallets out, allowing the team's new boss to spend large sums.
Felipe Anderson has moved from Lazio in a gigantic £36m deal, smashing the club's previous record transfer total. The signatures of ex-Borussia Dortmund man Andriy Yarmolenko and French centre-back Issa Diop have also been acquired for substantial fees.
Now Pellegrini is hopeful of landing another target, with the Hammers very much ready to put down a fee of €20m for Sanabria. West Ham would also table an extra €2.5m in potential bonus clauses if certain targets were to be met.
Finishing sixth in the Primera Division last term, the green side of Seville locked down an automatic spot in the Europa League group stages. If they are to sell Sanabria to West Ham, Alex Alegria would be left as their only out-and-out striker.
However, it is unlikely that the Irons would care about the fortunes of the Estadio Benito Villamarin club once a fee for Sanabria is acquiesced. Adding real depth to their squad this window, West Ham fans should be confident about a challenge for European places.