The 26-year-old joined Watford from Norwegian top flight club Bodo/Glimt on a free transfer in January, signing a five-and-a-half-year deal with the Championship side.
However, the Hornets were not the only club interested in acquiring the services of Zinckernagel, with Scottish giants Celtic also keen on his signature.
The Danish winger has revealed that Celtic were among a host of clubs that were interested in signing him on a free transfer before he put pen to paper on a deal with Watford.
Zinckernagel explained that he never came close to signing a deal with the Hoops, though there was interest from the Scottish Premiership outfit.
“We never got close to signing any deal with Celtic, but there was a lot of talking and a lot of interest, so it was something that I had to consider, for sure“, Zinckernagel told Watford’s official site.
“There were a few Championship clubs interested as well, but nothing that attracted me as much as Watford did.
“Watford were a much bigger club and it was an easy decision in the end.”
While Celtic lost their Scottish Premiership crown to Rangers, Zinckernagel went on to help Watford to promotion, contributing to six goals from 20 league games.