The 31-year-old striker’s contract is set to expire at the end of the season, and Schalke are understood to be resigned to losing him.
Although the Germans are aware that there’s little they can do to keep the prolific marksman, they are keen to get a fee for his services when the next transfer window opens.
But given his age and the short time remaining on his deal any sum is set to be as low as £3m.
This has alerted Liverpool, Arsenal and Spurs, who are all eyeing new goal-getters.
The Gunners failed with a late summer move for the former Real Madrid and AC Milan forward, but despite landing Danny Welbeck, Arsene Wenger may mount a fresh raid given his current injury woes.
Brendan Rodgers is similarly interested, with a lack of options beyond Mario Balotelli and Daniel Sturridge a concern.
Spurs are also in the running, as Mauricio Pochettino plots to add more goals to his Lilywhites side.
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