Lewis Hamilton was in impressive form as he headed Mercedes team-mate Nico Rosberg in first practice at the Monaco Grand Prix.
The world champion ended the session 0.101 seconds quicker than the German, with Ferrari's Sebastian Vettel third and Red Bull's Daniel Ricciardo fourth.
Hamilton tamed the difficult track faster than any of the other drivers.
He was well over a second - and sometimes nearly two - quicker than Rosberg in the opening half-hour.
Memorable skills from Hamilton
How quickly a driver can get to the limit at a track that is bounded by walls and run on normal city streets is always regarded as one of the best measures of the level of their naked talent.
Hamilton's first flying lap was 1.472 seconds quicker than Rosberg managed on his second lap.
Rosberg then went 0.1secs quicker, only for Hamilton to beat him by 1.839secs with a lap of one minute 18.302.
Their next laps, in succession, were:
Rosberg 1:19.129, Hamilton 1:17.381, Rosberg 1:18.585, Hamilton 1:16.588, Rosberg 1:18.480.
After a break, Rosberg did a 1:17.890, which Hamilton followed with a 1:16.097; Rosberg did a 1:15.835, then Hamilton a 1:15.537, before his team-mate finally got down to 1:15.638.
From Hamilton, it was the sort of performance that defines an image, that will be remembered down the years as illustrative of a towering talent.
He then made a couple of errors, cutting the chicane after misjudging his entry, and then going straight on at the first corner Ste Devote, without any damage.
Late in the session, Rosberg suffered a puncture to his left rear tyre after running over and dislodging a drain cover at Ste Devote, which subsequently punctured the front right tyre and shattered the front wing of McLaren's Jenson Button, the next car along.
In an incident-packed session, there were two crashes - Renault's Jolyon Palmer went too fast and wide into the fast Tabac corner and smashed into the barrier and Williams's Felipe Massa crashed at Ste Devote early in the session.
It was bad timing for the Englishman and the Brazilian, both of whose places in F1 are already looking vulnerable beyond the end of this season.
Vettel ended the session 0.419secs off Hamilton's pace and 0.352secs quicker than Ricciardo, who is one of two drivers using a new, upgraded Renault engine that is said to have about an extra 30bhp.
The other is Renault's Kevin Magnussen, who ended the session 17th fastest.
There was no sign of the promised improved form from McLaren-Honda, who arrived in Monaco expecting to be able qualify both cars in the top 10.
Fernando Alonso ended the session 13th, 1.882secs off the pace, two places and 0.082secs ahead of Button.