After an accomplished display against Hungary in his first start for England on Wednesday, Hart performed heroics for City at Tottenham on Saturday to earn his side a 0-0 draw and repay manager Roberto Mancini's faith in his ability.
Back at Eastlands after impressing for Birmingham City last season, Hart got the nod ahead of City's more experienced stopper Shay Given and after at least five sensational saves at White Hart Lane he looks to have cemented his place.
Tottenham manager Harry Redknapp was delighted with his side's vibrant performance and on another day, against another keeper, his side would have celebrated a handsome win.
"I couldn't ask for more from my team today but their keeper was fantastic," Redknapp told reporters.
"Joe was great today. It was good for the England manager to see that today and for English football to see a keeper who looks like he has got a great future."
Hart was part of England's World Cup squad but remained unused with Capello starting with Robert Green and ending the tournament with veteran David James after Green's blunder against the United States.
Neither was in the squad for the Hungary match and with former Tottenham Hotspur keeper Paul Robinson announcing his international retirement, England's goalkeeping options are limited.
But at least in 23-year-old Hart, the position appears to be in safe hands.
One save from Jermain Defoe in the first half against Spurs was top class while he also showed remarkable agility to claw away a deflected drive by Benoit Assou Ekotto and a dipping volley by Tom Huddlestone.
His handling was also exemplary and his decision making was spot-on as he twice raced off his line in the second half to snuff out goal threats.
"It was nice to get the decision to start," Hart told the BBC. "It was huge today. It was all I wanted to do football-wise to play for Man. City. But I have to keep on my toes because Shay is a great keeper and I love him to bits.
"It was great to play for England on Wednesday night and great to come out and do what I did today after being on loan for a year at Birmingham."
Mancini was cagey when asked about whether Hart had established himself as City's top keeper.
"For now," he said when asked if Hart is his No.1. "At this moment, Joe plays. Because we have four competitions, we need Shay."
