Lewis Hamilton retained his sizzling form to complete a practice double over Nico Rosberg ahead of Sunday's Italian Grand Prix.
Hamilton, 28 points ahead of Rosberg in the race for the championship, finished the opening session almost half-a-second clear of his Mercedes team-mate.
But the German, who became a father for the first time on Monday, will draw confidence from the fact that he was only 0.021 seconds shy of Hamilton's best lap of one minute 24.279 secs on Friday afternoon.
Mercedes have brought an upgraded engine with them to the high-speed Monza circuit and Hamilton and Rosberg were in a league of their own.
Italian Grand Prix in pictures
Italian Grand Prix in pictures
1/8 Friday first practice
Red Bull's Daniel Ricciardo approaches the Curve Grande
2/8 Friday first practice
Lewis Hamilton topped first practice in Monza
3/8 Friday first practice
Sergio Perez exits turn two in his Force India
4/8 Friday first practice
Red Bull team principal Christian Horner looks on from the pit wall
5/8 Friday first practice
Kimi Raikkonen will hope for improved fortunes in front of the home Ferrari crowd
6/8 Friday first practice
Hamilton negotiates the first chicane
7/8 Friday first practice
Jenson Button looks on from inside his McLaren cockpit
8/8 Friday first practice
Hamilton sports a new blond hairstyle ahead of practice
Indeed Sebastian Vettel, competing in his first Italian Grand Prix weekend for Ferrari in front of the partisan Tifosi, was three-quarters of a second slower than the Mercedes duo.
Force India, powered by Mercedes engines, appeared strong in opening practice and followed that up with Sergio Perez fourth and Nico Hulkenberg, who penned a new two-year contract with the team earlier this week, in fifth.
Pirelli, Formula One's sole tyre supplier, was under the spotlight in Monza after two high-profile blow-outs at the Belgian Grand Prix.
Vettel claimed he could have been killed following his penultimate lap puncture, whilst Rosberg was fortunate to emerge unscathed from a 190mph blow-out during practice.
Pirelli urged the teams to run higher tyre pressures - a concept which Hamilton claimed could have disastrous repercussions.
But Hamilton's fears did not come to fruition which will have come as great relief to the under-fire Italian tyre manufacturer.
McLaren's already difficult day took a turn for the worst during the second session when Jenson Button's running was restricted to just three laps.
After finishing ahead of only the Manor pair of Will Stevens and Roberto Merhi on Friday morning, the 2009 world champion, who will serve a five-place grid penalty, was called into the garage with a technical glitch and failed to re-emerge.
He finished over four seconds adrift of Hamilton in 19th and his team-mate Fernando Alonso fared little better. The Spaniard, slapped with a 10-place grid drop after taking on his ninth engine of the campaign here, was only 16th, albeit 2.6 sec slower than Hamilton.
McLaren will be joined at the back of the field for Sunday's race by Red Bull. Daniel Ricciardo has been penalised 25 places following an engine change and raft of new components. His team-mate Daniil Kvyat, who propped up the timings in the second session, has been hit with a 15-place grid drop.
Kimi Raikkonen was sixth for Ferrari with the Lotus pair of Romain Grosjean and Pastor Maldonado, Williams duo Valtteri Bottas and Felipe Massa rounding out the top 10.
Max Verstappen survived a trip into the gravel after he lost control of his Toro Rosso under breaking for the Ascari chicane.
Final Times after Second Practice:
1 Lewis Hamilton (Gbr) Mercedes GP 1min 24.279secs,
2 Nico Rosberg (Ger) Mercedes GP 1:24.300,
3 Sebastian Vettel (Ger) Ferrari 1:25.038,
4 Sergio Perez (Mex) Force India 1:25.278,
5 Nico Hulkenberg (Ger) Force India 1:25.325,
6 Kimi Raikkonen (Fin) Ferrari 1:25.380,
7 Romain Grosjean (Fra) Lotus F1 Team 1:25.497,
8 Pastor Maldonado (Ven) Lotus F1 Team 1:25.513,
9 Valtteri Bottas (Fin) Williams 1:25.647,
10 Felipe Massa (Bra) Williams 1:25.891,
11 Felipe Nasr (Bra) Sauber-Ferrari 1:26.114,
12 Marcus Ericsson (Swe) Sauber-Ferrari 1:26.133,
13 Daniel Ricciardo (Aus) Red Bull 1:26.222,
14 Max Verstappen (Ned) Scuderia Toro Rosso 1:26.454,
15 Carlos Sainz (Spa) Scuderia Toro Rosso 1:26.641,
16 Fernando Alonso (Spa) McLaren 1:26.966,
17 Will Stevens Manor (Gbr) Marussia F1 1:28.201,
18 Roberto Merhi (Spa) Manor Marussia F1 1:28.439,
19 Jenson Button (Gbr) McLaren 1:28.471,
20 Daniil Kvyat (Rus) Red Bull 1:28.723