Sarr landed in Turin on Monday evening and completed his medical at the club's J Medical centre, with the move coming together after Juventus missed out on an earlier target, Franck Kessié.
Tottenham manager Roberto De Zerbi had already confirmed the Senegal international had asked to leave north London, and the two clubs agreed a structure worth €30m in total: a €3m loan fee up front, with a further €27m due if Juventus exercise the option to sign him permanently.
That option becomes obligatory if Juventus qualify for the Champions League or Europa League and Sarr features in more than half of the club's matches this season. The 22-year-old will earn a reported €3m net per season, rising to a four-year deal at the same terms should the option be triggered.
Nick Woltemade's move from Newcastle is now also close to being finalised after the German forward gave his final personal green light to the transfer, according to Sky Sport's Gianluca Di Marzio.
The two clubs had already agreed terms, leaving only the player's consent outstanding; with that secured, Woltemade is due to fly to Italy on Tuesday to undergo his medical before signing his contract. The move is structured as a loan without any option to buy, reportedly worth around €5m, meaning Woltemade would return to Newcastle United at the end of the season regardless of his performances.
His arrival was unlocked by Jonathan David's departure on loan to Atlético Madrid, in a deal that includes a €25m buy option for the Canadian.
Juventus are also working on the other side of the ledger, with Atalanta preparing an offer for full-back Juan Cabal as soon as Tuesday. Sporting director Cristiano Giuntoli's side are expected to propose a loan with an option to buy that becomes an obligation, in a package worth between €8m and €9m — some way below the roughly €12m Juventus paid Bayer Leverkusen for the Colombian two summers ago.
Cabal, who can play at either full-back or as a centre-back, would provide Atalanta with squad depth after Sead Kolašinac started in defence on Sunday, though head coach Maurizio Sarri may prefer to use any incoming full-back budget on Alessio Romagnoli instead.
A departure for Cabal would also ease Juventus's wage bill, with talks over a separate deal involving Nicolás Tagliafico said to be progressing well; as with the David situation, Juventus are wary of leaving Cabal in a squad where head coach Luciano Spalletti has already made clear he is not part of his plans.