Chelsea must double their bid if they want to land Borussia Dortmund striker Robert Lewandowski. The Daily Mail says the European champions are understood to have made an initial offer of £13million rising to £17m for the Poland striker, 23, who has two years left on his contract.

Chelsea are considering alternatives to Napoli's expensive Edinson Cavani, yet Dortmund value Lewandowski closer to £35m.

Tottenham, Arsenal and Manchester United are also interested in Lewandowski. His representative Maik Barthel said: "A £13m transfer fee is not suitable."