The Red Devils confirmed the appointment of Amorim as their new head coach on Friday, although the 39-year-old will not officially take charge of the 20-time English champions until the November international break.
According to The Sun, Amorim has already identified a key transfer target for the club, viewing Diomande as the ideal acquisition, as he prepares to implement a three-man defence at Old Trafford.
The report claims that the Portuguese is initially planning to use Leny Yoro, once he returns to fitness, alongside Matthijs de Ligt and Lisandro Martinez in a back three.
However, Harry Maguire, Victor Lindelof and Jonny Evans could all leave the club next summer, and Amorim is said to be determined to add a young centre-back to the squad in 2025.
Amorim 'keen to sign Diomande for Man United'
Diomande, 20, is believed to be on the radar of a number of Premier League clubs, with Arsenal, Chelsea, Liverpool and Newcastle United all said to be interested in his services.
The Ivory Coast international has made 11 appearances for Sporting this season, while he has represented the Green and Whites on 66 occasions in all competitions since arriving from FC Midtjylland last year.
Diomande, who is valued at €40m (£33.5m) by transfermarkt, has a contract with his Lisbon club until June 2027, and a deal in January is highly unlikely, but the defender could be on the move next summer.
Sporting are likely to point to the €80m (£67m) release clause in his contract, though, with the club expected to stand firm when teams almost inevitability come calling for their star players in the not too distant future.
Which other Sporting players could Amorim target?
Viktor Gyokeres has starred under Amorim at Sporting, scoring 59 goals and registering 19 assists in 65 appearances for the Portuguese giants in all competitions, and the striker is believed to be on Man United's radar.
Geovany Quenda is an outstanding young talent at the club, with the 17-year-old making 15 appearances at first-team level this season, and Man United are said to have recently scouted the right-sided player.
It has also been claimed that Goncalo Inacio, Marcus Edwards and Pedro Goncalves are on Man United's radar, with the trio all proving to be important players under Amorim's management.
However, any business will likely have to wait until next summer, with Amorim unlikely to have significant funds available to improve the squad during the January transfer window.