In Ajax, Conservative cabinet minister Chris Alexander is in something of a grudge match with Liberal Mark Holland, whom he unseated in 2011 before becoming one of the Conservatives' fiercest partisans.
In Eglinton-Lawrence, Finance Minister Joe Oliver is up against Liberal Marco Mendicino, who won the party's nomination over ex-Conservative floor crosser Eve Adams, and the N-D-P is running former Saskatchewan finance minister Andrew Thomson.
Then there's the bellwether riding of Sarnia-Lambton, which has elected the winning party's candidate in every election since 1963.
Due to population growth, 30 new seats have been added this election -- half of them in Ontario. (The Canadian Press)