The Bundesliga club netted an initial £72million after the sale of Havertz, with further money owed in the shape of performance-related add-ons.
That big-money transfer has left Leverkusen will room to manoeuvre in the transfer market, having also sold Kevin Volland over to AS Monaco.
One area that is reported of interest to strengthen is right-back, with Bellerin the latest man in their sights.
Reports this month had linked Tottenham defender Serge Aruier with a move to Germany, with AC Milan also vying for his signature.
Now, according to The Telegraph, Leverkusen have joined Paris Saint-Germain and Juventus in the race for Bellerin.
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The Arsenal captain could be sold to free up further money for Mikel Arteta if the club’s £35million valuation is met, with Ainsley Maitland-Niles to replace him as first-choice.
WithTottenham are looking for £25million for Aurier, Bellerin would prove a more expensive option.
Equally, with clubs aware of Leverkusen’s sudden injection of cash, that will make negotiations tougher.