Diop is yet to prove his hefty summer transfer fee at West Ham.
He did, though, score in a 3-1 Carabao Cup win over AFC Wimbledon and he could start against Everton on Sunday at Goodison as The Hammers look to end a run of four straight Premier League defeats.
But Manuel Pellegrini will have been worried that summer signing Diop had inflicted an injury during training on teenage star Rice, who posted a picture of his right shin with four scars. He entitled the photo with: "Thank you my friend".
Rice, meanwhile, has been left on the West Ham bench as an unused substitute in the club's last two Premier League games, as controversy continues to surround the versatile star.
Indeed, Rice is yet to decide between playing for Ireland or England despite making three appearances for Ireland's national team. He is also in the final 12 months of his contract, after turning down an offer from the east Londoners.