O'Neill chose to start with a 4-4-2 formation at Ewood Park, with Gabby Agbonlahor and John Carew up front and youngster Fabian Delph in midfield.
However, many Villans will be fearing that their side are set to be over-run in the midfield department by Mark Hughes' City team, who name former Claret and Blue star Gareth Barry in their ranks.
Barry, has been a key man for City so far this season and should O'Neill fail to revert to his successful 4-5-1 formation then Villa will most likely be punished in the centre of the park.
The Northern Irishman may alternatively opt to recall Nigel Reo-Coker to combat Barry and Stephen Ireland and that would be the favoured line-up for the home faithful.
It may seem defensive to go with five in midfield but Villa play best on the counter-attack and a 4-5-1 could pay huge dividends on the night.
Richard Dunne, like Barry, will start against his former club as he partners James Collins at the heart of the Villa back four.
One of last season's key performers Luke Young again misses out due to a lack of match fitness.
City, are likely to recall Emmanuel Adebayor, who returns after serving a three match suspension but Robinho is out.