By ESPNSTAR.com staff
Roberto Mancini was left with a bitter pill to swallow after former player Adam Johnson struck the only goal of the game for Sunderland and consigned Manchester City to a 1-0 loss on a match day which saw title rivals Manchester United extend their lead to seven points after they beat Newcastle.
Speaking to the club's official website after the game, Hart did not consider the Red Devils' advantage to be unassailable.
"We've had leads, United have had the lead - it's to-ing and fro-ing at the moment," he said.
"We're a team of winners, it's hard and it hurts but we've got to move on. It is hard to lead and it is hard to chase too. We've clawed points back before, we proved it at the end of last year - we've just got to believe."
Sunderland's record against City is remarkable - they were the only side to leave the Etihad Stadium last season with a point - and Mancini joked afterwards that they would not travel to Wearside during the 2013-14 campaign.
In the short term, the Italian's focus will be on Saturday's trip to Norwich, where his side won 6-1 in April and where a repeat of that result, if not the scoreline, would be hugely welcome.
Hart said: "The only way we can change it is by winning here next year - but for now, we only have Norwich on our minds."
City had their chances at the Stadium of Light, but were denied by a combination of the woodwork and goalkeeper Simon Mignolet.
The Belgium international made three outstanding saves, from Yaya Toure and David Silva before the break and Sergio Aguero after it, and his efforts did not go unnoticed by the man at the opposite end of the pitch.
Hart said: "Simon Mignolet has had a magnificent game. He's a brilliant goalkeeper, I have watched him closely in other games.
"Sunderland defended for their lives and it just wouldn't go in for us."
The goalkeeper was disappointed that he failed to keep out compatriot Johnson's attempt, a strike he believed City were unlucky to concede.
"First and foremost someone stamped on Zaba [Pablo Zabaleta] – it was a blatantly obvious foul but what can you do?" Hart added.
"A few of our players have stopped but Johnno has seen me sniffing for a cross and he’s struck it well with that stiff ankle of his and it just deviated under my hand unfortunately."
Manchester City will take on Norwich for their Premier League fixture this weekend.