The Czech Republic international has fallen down the pecking order at the west London side after Jose Mourinho started Thibaut Courtois for wins against Burnley and Leicester City.
If I was Cech, I would leave immediately. He’s still young for a goalkeeper and he has a lot of football left in him
And Southall, who won two top-flight titles during his career, believes the 32-year-old shot stopper still has a promising career but can’t see Cech dislodging Courtois as Chelsea No1.
“Chelsea’s goalkeeping situation is tricky. They’ve two top class goalkeepers and one of them is always going to be upset,” Southall wrote in his Paddy Power blog.
“I would always go for the goalkeeper with more Premier League experience, but there’s a point when the manager needs to give the young player a chance or he’ll be off. Jose Mourinho has reached the point when he’s thinking ‘right, I can’t afford not to give Thibuat Courtois a run in the side because I’ll lose him otherwise.’
“On the other side, Petr Cech is probably a bit miffed he’s sitting on the bench. It’s a difficult balancing act to get right.”
Southall added: “If I was Cech, I would leave immediately. He’s still young for a goalkeeper and he has a lot of football left in him. Part of the reason is that Courtois is the real deal.
“Now that he’s got his chance, he’s going to fly and could be first choice until Christmas at least. There’s not many players who go out on loan and pick up a La Liga winners’ medal, a Europa League winners’ medal and play in a Champions League.
“Final before they make their debut for their parent club. There are a few things to work on, but he’s ready. Sometimes you just need to throw him in there and see how he goes.”
Southall added that he doesn’t believe Mourinho will allow Cech to leave Chelsea in the current transfer window.
“Jose won’t let Petr leave though. Not this season at least. He would want to keep him as an insurance policy if Courtois struggles to adapt to life in the Premier League,” Southall added.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news