The former Bayer Leverkusen attacker - who was previously on Arsenal's radar - made an instant impact at Villa Park upon his arrival last summer but never managed to nail down a consistent starting position.
Diaby still ended the campaign with a respectable 10 goals and nine assists from 54 matches in all competitions, but his form was not enough to earn him a spot in the France squad for Euro 2024.
The 25-year-old's contract in the West Midlands runs for another four seasons, but after Al-Nassr tried and failed to sign him last year, Al-Ittihad may have better luck convincing him to move to Saudi Arabia.
According to journalist Gianluigi Longari - via BirminghamLive - Diaby has now shaken hands on personal terms with the 2022-23 Saudi Pro League winners, who have Karim Benzema, N'Golo Kante and Fabinho in their ranks.
However, a transfer still hinges on Al-Ittihad agreeing a fee with Aston Villa, who will look to either make a profit on or demand the same £51.9m that they shelled out for his signature last summer.
Rennes 'reject' Bayern Munich bid for 19-year-old
Over in Ligue 1, Rennes are understood to have turned down an opening proposal from Bayern Munich for the services of 19-year-old attacker Desire Doue.
The 2005-born winger is thought to be at the heart of a multi-team transfer tussle thanks to his exploits in the 2023-24 season, where he registered four goals and five assists in 31 Ligue 1 appearances.
Doue also has two goals to show from his first two appearances for France's Under-23s side, and he will represent his country at the upcoming Olympic Games in Paris.
Arsenal and Tottenham Hotspur have both been heavily linked with a move for Doue, but according to Fabrizio Romano, it is Bayern who have firmed up their interest with an offer in excess of €35m (£29.5m).
However, Rennes immediately turned down the bid from Vincent Kompany's side, who have instead been told that it would take an offer north of €60m (£50.5m) to prise Doue away from Roazhon Park, where he is under contract for two more seasons.
It is unclear whether Bayern are preparing a revised bid for Doue, as the Bundesliga powerhouses are also waiting for Paris Saint-Germain's Xavi Simons - another prime target - to make a decision on his future.
Pepe Reina to continue career with Como?
At the other end of the experience scale, veteran Spanish goalkeeper Pepe Reina - 22 years Doue's senior at 41 - supposedly has no plans to hang up his gloves just yet.
The former Liverpool goalkeeper became a free agent when his Villarreal contract expired at the end of June, and his age has naturally led to speculation about a possible retirement.
However, Reina is still intent on playing at the top level for a little while longer, and a separate update from Romano claims that the former Spain international is on the verge of joining Italian side Como.
The goalkeeper - who celebrates his 42nd birthday in August - is expected to sign a one-year contract with Osian Roberts's side, who were promoted back to Serie A from the second tier last season.
Como will represent the ninth club that Reina has represented in his lengthy career, having previously turned out for Villarreal, Barcelona, Liverpool, Aston Villa, AC Milan, Napoli and Lazio.
Reina made 12 appearances for the Yellow Submarine in the 2023-24 campaign and is expected to be one of a few marquee arrivals for Villarreal this summer alongside Alberto Moreno and Raphael Varane.
Borussia Dortmund to poach Arsenal academy product?
From a 1982-born shot-stopper to a player who had not even been born when Reina joined Liverpool, Arsenal starlet Ayden Heaven is reportedly attracting glances from Borussia Dortmund.
The 17-year-old is yet to earn his first-team debut for Mikel Arteta's side, but he did make the bench for the first leg of their last-16 Champions League clash with Porto, which ended in a 1-0 defeat.
Heaven featured regularly for the Under-18s and Under-21s in the 2023-24 season, but he has not been rewarded with a professional contract and sees his scholarship terms expire in just under 12 months' time.
Keen to take advantage of the uncertainty, the Evening Standard claims that Dortmund are keeping a close eye on the teenager, who is primarily a centre-back but is also comfortable as a left-back and in the heart of midfield.
Dortmund, who have become renowned for their development of young stars, could have to fend off Premier League suitors to win the race for Heaven, though, while Arsenal have not given up hope of keeping him at the Emirates either.
Heaven previously plied his trade in the West Ham United academy before joining Arsenal, who have already seen Reuell Walters, Amario Cozier-Duberry and Mika Biereth leave the club this summer.