The 23-year-old winger "bitterly regrets" signing a long-term deal with the Bundesliga club instead of making the switch to Anfield
Former Schalke winger Donis Avdijaj says turning down the chance to join Liverpool is the biggest mistake he has made in his career.
Avdijaj spent seven years with Schalke, having joined at the age of 14 in 2011 and progressed through the youth system.
He left on a free transfer to Willem II in 2018 having made 12 appearances for the Schalke first-team.
The Kosovo international was released by the Dutch club in March 2019 and was snapped up by Trabzonspor that summer, though he left a few months later to join Hearts in January. The 23-year-old finds himself without a club again as his time at Hearts has come to an end.
Avdijaj admits his career could have gone another way as the Premier League champions and Real Madrid wanted him a few years ago.
He told Sport1 : "My biggest mistake, which I bitterly regret, was turning down another mega offer from Liverpool before I signed the long contract with Schalke, which was a matter close to my heart. I also had one from Real Madrid."
However the winger remains optimistic about his future, as he has already received several offers for next season.
"I already have a lot of requests from clubs," he said. "I have to probe first. I have to make a plan for myself, where I want to go, what is best for me, and how to proceed. There are a lot of talks going on."
He added: "I've never doubted myself. I am still convinced of myself. In most of my past stations, the sporting side speaks for itself.
"I convinced athletically in Netherlands. After a long break without football, I played 20 games at Trabzonspor and almost played through in the Europa League. I also had 10 or 12 games at Hearts and you don't know how things would have gone if the coronavirus pandemic hadn't intervened.
"I could have had a bit more luck in Scotland, but if I continue to believe in myself, train hard and play well in the next club, I'll get back that little bit of luck that I might have been missing lately.
"I know that it is up to me what my sporting future looks like. It certainly doesn't matter whether I've played at one club for five years or have 10 clubs in five years. In the end, only one thing counts for me, namely that I can play football and show what I can do."