Premier League clubs are on red alert with Robert Lewandowski's future at Borussia Dortmund thrown into doubt. The Mirror says Manchester United were willing to pay £16m for Lewandowski in the summer.
Their interest cooled in Lewandowski, 24, once they signed Robin van Persie.
The German champions fear losing their star man for nothing and could be ready to cash-in.
Dortmund chief executive Aki Watzke said: "We will sit down and discuss what to do next if Robert does not extend his contact."