Sexton remains the favourite the No10 shirt when Britain and Ireland's elite head Down Under but his hamstring injury has paved the way for Madigan to enjoy regular rugby and the understudy has made the most of that opportunity.
Madigan pulled the strings as Leinster thumped London Wasps 48-28 in the Amlin Challenge Cup quarter-final last Friday, finishing with a personal tally of 28 points, scoring a sublime individual try and proving a constant threat with his ability to break the gain line.
He only made his international debut against France this spring but Ireland and Leinster team-mate Fergus McFadden believes big things could be around the corner when Warren Gatland names his touring party on April 30.
"At this time of the year one or two big performances could get you on a Lions tour," McFadden told the Irish Independent.
"Whether it's Ian, there are going to be wildcards brought to Australia, there is one every Lions tour.
"I suppose from Ian's perspective he has got to keep his starting place because Jonny is coming back now.
"If he keeps his fitness, I imagine he will be in the mix to go to Australia as well.
"They are two very different players, Ian and Jonny, but they both have their positives in different aspects."
Sexton is in line to feature when Leinster face Munster at Thomond Park this Saturday having not played since Ireland's defeat to England on February 10.