24-year-old Basham left Preston after his contract expired and is now in search of first team football, something he hopes he can gain at Pittodrie.
Riza, 22, also hopes that he can earn a permanent move to Aberdeen. The former Arsenal trainee left West Ham at the end of last season and has only just finished training with Cambridge United.
Dons boss Ebbe Skovdahl said: "It would be a good chance to have a look at the two of them."
Aberdeen have also launched a bid for Deloumeaux, the French defender who Motherwell's administrators are desperate to get of the Fir Park wage bill.
He was offered to Coventry City for £50,000 last week, half the price Well paid Le Havre for him last season.
The Dons are now in talks with their SPL rivals and could conclude a deal this week.
