The 25-year-old has gone to Saudi Arabia to undergo a medical examination and finalize his transfer, following just one season at Villa Park.
Diaby moved to Villa from Bayer Leverkusen for a club record fee, reportedly £51.9m, last summer. However, manager Unai Emery has chosen to sell the French international.
This decision follows the club’s re-signing of Jaden Philogene from Hull for approximately £13.5m earlier this month. They believe the academy graduate will have a significant impact upon his return.
Diaby played 54 matches for Villa, scoring 10 goals, and contributed to their fourth-place finish in the Premier League, securing a spot in the Champions League.
As Villa prepares for the new season, they are reshaping their squad, having sold midfielder Douglas Luiz to Juventus for £42.4m last month.
The club has brought in Samuel Iling-Junior and Enzo Barrenechea from the Italian side, while left-back Ian Maatsen joined from Chelsea for £35m and winger Lewis Dobbin came from Everton for about £9m.
Additionally, Villa recently completed the £50m signing of Everton midfielder Amadou Onana.
