The 23-year-old midfielder has been pushed further down the pecking order following the £198million arrival of Neymar from Barcelona.
According to The Times, the London club could make another move for the 23-year-old having being knocked back several times in the past.
He could be available for around £32m.
The German World Cup winner arrived in the French capital in January for £35.5m from Wolfsburg.
But already he is said to have fallen out of favour with boss Unai Emery – and that could alert Premier League giants Arsenal – and Liverpool.