Premier League clubs are on alert after a training ground bust-up at Bayern Munich.
The Mirror says Bayern's miserable end to the season continued in training on Wednesday, as Robert Lewandowski and Jerome Boateng clashed.
Lewandowski is unsettled at Bayern and has been linked with Manchester United, Liverpool and Arsenal in recent weeks.
Boateng came sliding in to make a challenge on the former Borussia Dortmund striker, with the ball nowhere in sight.
The pair had to be separated by Bayern skipper Philipp Lahm and a number of other teammates, who sought to diffuse the tension.
However, as they pointed and shouted at one another, Bayern chief Pep Guardiola ordered the duo off the field and into the changing rooms.