The Algerian joined Leicester in 2016 following their unlikely title triumph for a club-record £28m, but he struggled to impress and scored just eight goals during his first season with the club.
Those figures were a far cry from the totals that the 29-year-old scored when he played for Sporting Lisbon and the powerful striker has now revealed that he held talks with former manager Marco Silva over a move to Watford during the summer.
Speaking to Algerian publication 'Le Buteur', Slimani said: "I had a conversation with Marco Silva, who was my coach at Sporting, and he was very interested in having me on the team.
"He presented me with a magnificent project, but unfortunately it did not materialise. The leaders of Leicester City told me they wanted me here.
"But they are things of the past, now I am focused on my team."
The capture of a striker of Slimani's caliber would have been something of a coup for the 'Hornets' and it is possible that the club will revisit the move in January.
Slimani has three-and-a-half years left on his contract at the King Power and is yet to find the net in the Premier League so far this campaign.