The 24-year-old Uruguay international, who played for his country at the World Cup, has become a prime target for Tigers manager Steve Bruce, who has abandoned interest in Blackburn's Jordan Rhodes.
Reports in Italy have suggested a deal worth around £9.5million for Hernandez is almost complete, however Bruce is looking at it from a more cautious perspective.
Bruce said, according to the Daily Express: "It's delicate, but if we can pull it off it will be a record for the club.
"He's a hell of a player, but there's work to be done. It would be a huge one for us."
Hull sold Long to Southampton for £12million earlier this month, after which they were linked with Rhodes, but Bruce said on Wednesday that potential deal was "dead and buried".
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