Grealish has scored two goals and made three assists from nine matches since returning from the World Cu
Manchester City returned to the top of the Premier League for the first time since November as they leapfrogged leaders Arsenal with a vital victory at Emirates Stadium.
The reigning champions turned on the power in the second half in the biggest game of the domestic season as Arsenal paid a heavy price for individual errors, reports BBC.
Takehiro Tomiyasu's poor backpass allowed Kevin de Bruyne to loft a finish over Arsenal goalkeeper Aaron Ramsdale after 24 minutes but Arsenal deservedly drew level three minutes before half-time, Bukayo Saka scoring from the spot after City goalkeeper Ederson fouled Eddie Nketiah.
City, lacking spark in the opening phase, improved after the break and had a penalty of their own ruled out for offside against Erling Haaland before they showed a ruthless streak to punish Arsenal.
Gabriel lost possession to allow Bernardo Silva and Haaland to set up Jack Grealish for a deflected finish after 72 minutes before they ended Arsenal's hopes with 10 minutes left.
Inevitably, Haaland was the scorer from De Bruyne's pass to put City top on goal difference having played one game more than Arsenal.
Man City strike telling blow
City have returned to the top of the Premier League by striking a devastating blow on the long-time leaders.
City, by their own standards, have not quite hit the heights this season but they now find themselves looking down on Arsenal once more, albeit the Gunners have a game in hand.
Even here, City lacked their usual fluency in the first 45 minutes and Arsenal arguably deserved more than being on level terms at the interval.
And yet, once they moved through the gears in the second half City carried enough threat to put Arsenal away and return to the position they have occupied so often in recent years.
City gratefully accepted the gifts Arsenal offered and once Grealish restored their lead - a touch off the luckless Tomiyasu sending his shot past Ramsdale - this game was done.
Haaland's goal emphasised City's supremacy and they closed out the win with ease, the celebrations at the final whistle reflecting the significance of the result.
Arsenal must hold nerve
This defeat will be a bitter blow to Arsenal, coming as it did in front of their own supporters.
It continued a recent stumble in which they have lost at City in the FA Cup and at Everton in the league, drawn controversially against Brentford on Saturday and now another damaging defeat here.
Arsenal and manager Mikel Arteta must not get too down on themselves, although the scale of the setback here cannot be underestimated in the context of the title race.
The Gunners were excellent in the first 45 minutes but Tomiyasu's poor back pass and Gabriel's concession of possession were the sort of mistakes you simply cannot make against this class of opponent.
Arsenal must regroup and realise they are still right at the heart of the Premier League title pursuit - but no-one can escape the damage done by this result.