Enzo Maresca: Rory Delap training with Chelsea but Marc Guiu in line to face Sunderland

Chelsea boss Enzo Maresca believes being ruthless with Marc Guiu has changed the teenage striker for the better after telling him he was unhappy “in all the ways” with his training efforts.

Maresca has summer signing Liam Delap back in training, albeit not quite ready to return to first-team action after a hamstring injury lay-off.

Delap has been sidelined since August, and it was his blow that prompted Chelsea to recall Spaniard Guiu, 19, from his loan at Sunderland after just three matches.

Sunderland are the visitors to Stamford Bridge on Saturday and the game comes just too early for Delap, who could return to action against Wolves in the EFL Cup next week.

Chelsea have relied on Joao Pedro as their main striker, with Guiu yet to start for them in the Premier League this season, but he played from the first minute and scored against Ajax in the Champions League on Wednesday.

“I had a chat with Marc two weeks ago,” Maresca said. “I told him I didn’t like the way he was training and he needed to change. It changed and he got the chance.

“He was not training well, in all the ways. I don’t know why, but that’s sometimes the way with young ones and you need to go slowly with them.

“Since we chatted, it is top and fantastic and he is working very well.”

Guiu has featured as a substitute in two Premier League matches, against Liverpool and Nottingham Forest, where his movement helped to create space for goals -including Estevao Willian’s late winner against last season’s champions before the international break.

His involvement has also allowed Joao Pedro to shift to a number 10 role, where Maresca believes he “plays better”.

Asked if Guiu could now start his first Premier League game of the season, Maresca said: “Absolutely, yes. He is ready to start.”