The Italian club will be playing in the Serie B next term after finishing bottom of Serie A.
Radrizzani is looking to sell Leeds, and acquiring Sampdoria is expected to boost his chances of doing so.
49ers Enterprises want to complete a full takeover, and while the club’s value has taken a hit following relegation, the Americans are still keen.
Radrizzani owns a 56% stake in the Elland Road club, while the remaining 44% belongs to the 49ers.
The Italian businessman is not the only person buying Sampdoria, with his business partner Matteo Manfredi also involved.
They will look to finalise a consortium and due diligence is being done with initial paperwork signed.
The Leeds owner plans to inject €40 million into the club after the takeover is completed.
Both parties will still address concerns over debt restructuring, but the process is expected to go through.
Radrizzani took partial control of Leeds in January 2017 after acquiring 50% of the club from Massimo Cellino.
The 48-year-old completed a full takeover four months later and completed the purchase of Elland Road in June.
They escaped relegation on the last day of last season and were hoping for a similar miracle last Sunday.
Leeds will look to bounce back immediately, and 49ers Enterprises must get plenty of things right.
The business arm of the NFL club San Francisco 49ers bought shares in the club to become a minority investor in 2018 and could be a few weeks away from a full takeover.
- Watford hand Valerien Ismael new contract
- Crystal Palace ace Eberechi Eze facing six weeks on sidelines with hamstring injury
- Newcastle handed major injury setbacks ahead of PSG Champions League clash
- Valencia chief insists Javi Guerra not for sale amid Manchester United and Newcastle United interest
- Rangers considering Ryan Lowe for managerial vacancy following Michael Beale’s dismissal