The 30-year-old failed to secure a deadline day move away from Stamford Bridge despite reported interest from Bayern Munich and Scottish champions Celtic and this week shared pictures of himself training alone, away from his teammates.
Sterling been exiled from Maresca’s squad since returning from last season’s loan spell with Arsenal despite being paid a whopping £325,000-a-week by The Blues who are desperate to get rid of him.
Speaking on talkSPORT, former Premier League striker Gabby Agbonlahor admits he is worried for Sterling’s mental health as his time at the club worsens.
"Players felt like, 'Oh, I can't speak to the bomb squad group. Don't want to get caught speaking to them.' It makes you feel so low.
"For Raheem Sterling, yes, last season wasn't at his best. 17 Premier League games for Arsenal, only four starts, no goals, two assists. But he's only 30, Raheem Sterling now.
"82 England caps, 20 goals, four Premier League titles, five League Cups, one FA Cup. And he's training on his own, being treated so badly by the manager.
"This is the problem that I have with some fans, because they moan about players like Isak, like Wissa, wanting to leave. But when a club doesn't want you, they will treat you like absolute garbage.
"They will make you train at this time. They will make you sit in the changing room on your own, away from your teammates.
"What about Raheem Sterling's mental health? What about (Axel) Disasi's mental health?"
Sterling must now train by himself as his west London nightmare continues and he will be eagerly awaiting the January transfer window where he could escape from the side to find first team football and join a club who appreciate him more.