Coming into the contest with a slender one-point lead at the top of Serie A, the Nerazzurri travelled to their nearest challengers knowing a win would see them take a giant step towards retaining the title.
Given the magnitude of the match, a cagey opening 20 minutes was to be expected, but it was Inter who took the lead midway through the first half when Federico Dimarco curled a sublime free-kick into the top corner for his fourth goal of the season.
Winless across their last four league games (D3, L1), Napoli knew a positive response was needed, and Romelu Lukaku came close to a leveller when his sharp volley drifted narrowly wide of the near post.
The hosts continued to probe for a route back into the contest with half-time approaching, but Alessandro Bastoni stood firm in the Inter defence, producing a brilliant block to deny Lukaku from tapping home inside the six-yard box.
Napoli remained on the front foot following the restart, with Giacomo Raspadori seeing a close-range effort blocked and Stanislav Lobotka firing wastefully over from the edge of the box.
Despite seeing plenty of the ball, clear-cut chances came at a premium for Antonio Conte’s men, as Scott McTominay’s powerful drive was comfortably repelled by Josep Martinez in the visitors’ goal.
With time ticking into the final quarter-hour, Napoli looked to up the ante in pursuit of an equaliser and their pressure finally paid dividends with three minutes remaining.
Lobotka threaded a clever pass into the path of substitute Billing, and after Martinez had saved his initial strike, the Danish midfielder slotted into the bottom corner to restore parity.
That goal set up a fascinating finale, but despite some late pressure from the hosts, both sides ultimately had to settle for a share of the spoils, as Inter maintained their slender lead at the summit.