This looks like a match between two sides who create chances at a similar rate, with the difference sitting in the schedule and the back lines. Napoli are leaking chances in bursts, while the league leaders arrive rested and steady on the ball. It is less about a clear favourite and more about who is in better shape on the day.
Napoli's recent run mixes league and Champions League games, and their defence has allowed big chances in several of them: 18 goals conceded in 10, with two straight losses at Juventus and Porto. They have only about three and a half days of rest. Lazio sit top of the league, keep the ball more than half the time and have rested close to seven days.
The key matchup is Napoli's patched back line against Lazio's patient build-up. Lazio have won five in a row with the same absences in place, including a replacement goalkeeper, so those gaps are already in their numbers. Their chance volume over eight league games is at least as good as Napoli's over ten mixed games.
I expect chances at both ends, with Napoli pushing early at home and Lazio finding space as the game stretches. That's why I'm siding with Lazio, protected against a level finish.