Saka failed to feature in the second half of the Gunners' 2-2 draw with Crystal Palace on Monday night, after being substituted at half time due to an injury caused by a challenge from Palace's James McArthur.
Meanwhile, Tierney also started on Monday but was forced to sit out training for much of this week due to bruising.
However, the duo have since been pictured in training with their teammates on Thursday, and now look set to feature against Dean Smith's Villa at the Emirates Stadium.
Having the pair available will be a welcome boost for Gunners boss Mikel Arteta, who will be looking for his side to put in an improved display on Friday after being held to back-to-back draws against Palace and Brighton & Hove Albion.
Arsenal required a stoppage-time equaliser from substitute Alexandre Lacazette on Monday in order to avoid a shock defeat to the Eagles, who are managed by former player Patrick Vieira. body check tags ::