The hosts raced into a two-goal lead after Jarrod Bowen's first-half double, but Grealish and City responded superbly after the interval.
The Englishman halved the deficit four minutes into the second-half with a deflected strike, before Vladimir Coufal headed into his own net from a Riyad Mahrez cross.
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The Algerian then missed a late penalty but Grealish believes that given the position at half-time, a point is great value.
"It was a day of mixed emotions," he said. At the start we dominated the game. We knew they would sit in an counter attack with [Michail] Antonio, it’s perfect for them to play the ball in behind, that's what they did.
"At half-time we would have taken a draw all day long, we recover now and have a good week of training and look to win next Sunday. We had the penalty to win, but then like I said, at half time we would have taken the draw.
"At full-time you think could we have won the game? They had chances too but we had the better ones.
"We dominated the game and the ball, come the end, it’s one of them, it’s mixed emotions."
The 26-year-old scored his first away league goal for Pep Guardiola's side to spark the comeback at the London Stadium, showing great technique to volley towards goal as the ball deflected off Craig Dawson and beyond Lukasz Fabianski.
"About time, isn’t it?! I just try to score goals," he said when reacting to his goal. "The manager tells me keep getting into the box.
"I hit the target. I’ve scored quite a few goals at this ground in my career, hopefully I can play here more often!"
The valuable point puts us four points ahead of title rivals Liverpool, who could close the gap to one point with a victory on Tuesday, meaning the title could be decided in the final game week of the campaign, with City facing Aston Villa.
"You want to make it as easier as you can for yourselves," admitted Grealish. "We have a great home record, all our fans will be behind us, it will be a great day. Fingers crossed we can go and get the win.
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"It just had to be against Aston Villa didn't it! It doesn't matter about me and it doesn’t matter who we play against.
"We will try to get all three points. It’ll be different for me, I’ve never had that before to play for a game to win all three points. I’m looking forward to it I can’t wait."