The German defender is one of the several Leeds players who are expected to leave the Whites in the ongoing transfer window.
A relegation clause in his contract is claimed to allow Koch to leave on a free deal and there are more than a few clubs interested in signing him.
Manchester United have him on their shortlist of targets given his Premier League experience and he has suitors in Germany as well.
And now Leverkusen have also joined to race to sign the Leeds defender.
With Jonathan Tah expected to leave Leverkusen this summer, the Germany international has been identified as a replacement.
The Leeds defender has also been linked with a move to another Bundesliga club in the shape of Eintracht Frankfurt in the ongoing window.
But there is a strong possibility that Koch will continue playing in the Premier League next season.
An unnamed Premier League club are claimed to be in pole position to sign the centre-back on a transfer this summer.
