Mauro Icardi wasted a glorious stoppage-time chance as Inter missed the opportunity to put further distance between themselves and city rivals AC Milan in the race for Champions League qualification with a 0-0 draw at San Siro.
Having looked likely to win Derby della Madonnina for a second time this term, Luciano Spalletti will know Inter should have more than a two-point cushion over fifth-placed Lazio.
The scoreless draw was enough to maintain their eight-point advantage over Milan, meaning Lazio are now the main side who can deny them a return to Europe's top club competition.
Icardi, scorer of a sublime hat-trick that gave Inter a 3-2 win in the teams' last league meeting, appeared to have scored what would have been the decisive goal late in a frenetic first half, only for the VAR to rule him offside.
Leonardo Bonucci and Patrick Cutrone did force Samir Handanovic into a pair of smart saves either side of half-time but, in truth, the Rossoneri struggled to carve out the clear openings required to close the gap.
And they should have been punished by the normally reliable Icardi, but with the goal gaping on two occasions he somehow managed to miss the target, leaving a frustrated Inter to settle for a point.
The raised stakes of an encounter Gattuso described pre-match as being "back to something significant" were evident from the intense early exchanges as Franck Kessie got in the way of Rafinha's third-minute shot.
Gianluigi Donnarumma was then forced to parry a stinging Antonio Candreva effort, while Marcelo Brozovic twice curled harmlessly wide either side of that attempt.
Inter's early momentum would have been completely erased if not for the incredible reflexes of Handanovic, who somehow clawed Bonucci's flick-on header away the bottom right corner.
Far from assured at the other end, Milan were fortunate that Ivan Perisic's loose touch cost him a better sight of goal midway through an entertaining half.
And they earned another reprieve when the VAR deemed Icardi to have marginally strayed into an offside position prior to firing in what looked to be the opener.