The pair combined emphatically last campaign to fire Leicester City to the title, but their partnership has failed to hit the same heights this season.
When Leicester City achieved the impossible and won the Premier League in 2015-16, nobody expected them to follow it up with a scintillating 2016-17 season. In fact, it was widely accepted that they could be forgiven a considerable dip in form after the heights that they hit.
But what was a dip in form is now a dangerously poor run of results and, more worryingly, performances for the Foxes. Saturday's 2-1 defeat to Watford leaves them on 12 points after 12 games, and only two points off relegation.
This time last year, after 13 games played, Leicester were top of the table with 28 points. Claudio Ranieri's men had just beaten Newcastle United 3-0, and Jamie Vardy had just equalled Ruud van Nistelrooy's record of scoring in 10 consecutive Premier League matches.
But the England striker has not been the same player this term, and this is in no small part due to the failing of his connection with chief provider Riyad Mahrez, who has not emulated his PFA Player of the Year-winning form.
The difference between the pair last season and this campaign is staggering, and one statistic highlights this above all others. In 365 minutes of action that the two have played together since September 17, Mahrez has only made one successful pass to Vardy.
And, looking at the season as a whole, the Algerian has passed to Vardy successfully on only nine occasions in 12 matches. With his service severely diminished, it is easy to see why Vardy has only netted three times in all competition this season, and hasn't scored for over two months for his club.
Mahrez is obviously suffering a significant regress in form - compared to his 18 assists and 10 goals last term, he only has two goals and two assists so far this season. And his performances are affecting Vardy's, who relied on the partnership between the two for many of his 24 league goals in 2015-16.
The breakdown in the Mahrez/Vardy partnership is a significant factor in Leicester's current ill fortunes. They have lost six games already this season and desperately need to improve their league form. They face Middlesbrough next in the Premier League at the King Power Stadium.
Their performances in the Champions League, on the other hand, has been very impressive, and qualification for the last 16 will be assured with a win against Club Brugge on Tuesday.