John Percy of The Telegraph broke the news and reports that Hart has already been informed of the decision, which hasn't been announced by the club. Pantilimon made a strong case to draw a league start with a clean sheet against Newcastle in midweek Capital One Cup play:
The England goalkeeper has been agonising over his place in Manuel Pelligrini's starting team since conceding Chelsea's winning goal at Stamford Bridge last week after a mix-up with defender Matija Nastajic.
Telegraph Sport understands Hart has today been told he will be left out of the team to face Norwich in favour of Costel Pantilimon.
Hart was a key piece for City during their run to the Premier League championship two seasons ago. He also emerged as the potential solution to England's recent goalkeeping woes at the international level in the process.
He struggled to maintain top form last season, however, and that often-lackluster play has carried over into the new campaign. His mistake late in last week's loss to Chelsea, which allowed Fernando Torres to net a late winner, was the latest example of his struggles.
With City quickly falling behind in the title chase, Pellegrini was forced to make a tough decision between sticking with Hart or giving Pantilimon a chance to prove himself after limited playing time in recent years. He's apparently chosen the latter option.
It will be interesting to see how Hart responds. It's a World Cup campaign, and if he's going to lock down the starting spot for England, he needs as many opportunities as possible at the club level to prove he warrants the call.
Prior to making the decision, Pellegrini had been firmly on the fence about benching his star keeper, according to The Guardian:
Speaking after the cup win over Newcastle, Pellegrini said: "I will start to think about the game against Norwich on Thursday. One goalkeeper can play but the other will have our full support. We will think about it.
"[Pantilimon] is a good player and is not playing too much because Joe Hart played this year and last year, but I trust him and for him and for the whole team to keep a clean sheet after six games is very important."
Brad Friedel had previously expressed concern that dropping Hart would impact his confidence, according to The Independent:
Friedel helped Tottenham reach the League Cup quarter-finals with a penalty shoot-out victory over Hull, and he told talkSPORT: "All goalkeepers go through ups and down.
"Goalkeeping is very much a confidence position. Joe has never struck me as a person who lacks in the confidence department.
"You just never know with these things. That's why it's not as easy as, 'Right, we're going to drop Joe Hart', because you don't want to lose the best Joe Hart, because the best Joe Hart is England's number one."
At the same time, City have to worry about winning matches, and it's hard to argue against giving Pantilimon a chance right now. Whether the Romanian takes over the top spot on a regular basis or this will be a match-by-match decision is unclear, though.
For now, Pantilimon is expected to draw the start against Norwich, and supporters will have to see what happens from there.