Charles Leclerc continued his good form to complete a practice double for the Italian Grand Prix.
Just five days after he registered the maiden victory of his Formula One career in Belgium, Leclerc ended both rain-interrupted sessions in Monza at the top of the leader board.
Lewis Hamilton, who heads into Sunday's final round of the European season with a 65-point championship lead, trailed Leclerc by just seven hundredths of a second.
Leclerc's Ferrari team-mate Sebastian Vettel finished third ahead of Valtteri Bottas for Mercedes.
Leclerc delivered an impressive performance last time out at Spa-Francorchamps, dominating throughout practice, sealing pole position before marching to the chequered flag.
And the young Monegasque driver seems in fine fettle here, too, after he set the pace in both sessions.
Despite drops of rain, the afternoon running took part largely in dry conditions, and the high-speed Monza layout appears to suit the grunt of the Ferrari engine.
But Mercedes' Hamilton, who is bidding for a record sixth win in Italy, is in contention to deny Leclerc back-to-back victories, and Ferrari their first home win in almost a decade.
Fernando Alonso was the last driver to triumph in Monza for Ferrari in 2010, with Hamilton winning four of the last five races staged here.
Norris was struck by further mechanical problems in second practice and finished a lowly 18th.
Earlier, the opening running was suspended twice after Kimi Raikkonen and Sergio Perez crashed out.
In wet conditions, both men lost control of their cars and ended up in the wall. Raikkonen finished 14th in the day's concluding running, with Perez 16th.