The Villans told the club’s official website

Despite impressing in the recent match against Wigan Athletic, the 25-year-old was withdrawn from England’s squad due to back injury.
Initially, it was expected that Agbonlahor would be out of action for few weeks. However, McLeish has confirmed that the English striker has undergone successful fitness test and will be available for selection against Manchester City.
The Villans told the club’s official website, "Gabby has trained this week and as long as nothing interrupts his training schedule, he should be fine for City.”
However, Aston Villa will be without the services of Nathan Delfouneso after the English striker sustained a hamstring injury during England Under-21 win against Iceland.
McLeish has expressed his disappointed over the unavailability of Nathan and has confirmed that the English striker will miss at least next two matches. 
The Scotsman added, "I am disappointed for Nathan as I think his hamstring prevented him playing the rest of the game. Also it has maybe cost him a couple of games here.”
"He has got to do a bit of preventative work in the gym but I'm sure Adrian Lamb will help him attain stronger hamstrings that enable him to make his bursts from start to finish in games," Alex McLeish concluded.
Aston Villa will visit Premier League current joint leaders, Manchester City this weekend. The Villans are currently placed seventh in the League standings with 11 points in seven matches.
The Villans are currently unbeaten in the league and Alex McLeish’s men will be looking to stretch their unbeaten record when they face Roberto Mancini’s men.