The title hopefuls ran out 8-0 winners over Al’s Bar at Sevenoaks Road to make it 31 points from a possible 36 this season.
Cross Keys have two games in hand on second-placed Padnell Rovers, so four points from their remaining four matches will be enough to secure top spot.
Al’s Bar dropped a position to sixth, but are only two points outside the top three.
1. Action from the City of Portsmouth Sunday League Division Four match between Cross Keys Athletic (green shirts) and Al's Bar
Action from the City of Portsmouth Sunday League Division Four match between Cross Keys Athletic (green shirts) and Al's Bar. Picture: Kevin Shipp Photo: Kevin Shipp
2. Cross Keys Athletic score one of their eight goals against Al's Bar
Cross Keys Athletic score one of their eight goals against Al's Bar. Picture: Kevin Shipp Photo: Kevin Shipp
3. Cross Keys Athletic score one of their eight goals against Al's Bar
Cross Keys Athletic score one of their eight goals against Al's Bar. Picture: Kevin Shipp Photo: Kevin Shipp
4. Action from the City of Portsmouth Sunday League Division Four match between Cross Keys Athletic (green shirts) and Al's Bar
Action from the City of Portsmouth Sunday League Division Four match between Cross Keys Athletic (green shirts) and Al's Bar. Picture: Kevin Shipp Photo: Kevin Shipp