Reigning World Champ Sebastian Vettel proved that it doesn't matter when and it doesn't matter where, he is the man to beat in F1.
The German, the winner of four of this season's five races, clocked a 1:16.619 around the streets of Monaco to set the pace in Thursday's opening practice session.
However, the results could have been different had it not been for traffic in Fernando Alonso's final sector on his final lap, which saw him miss out on the P1 slot by 0.113s.
Nico Rosberg was third quickest ahead of Felipe Massa, Lewis Hamilton and Jenson Button while Pastor Maldonado had a good session, finishing in seventh place.
However, he was a full second behind Button, showing the advantage that the top teams have over the midfield runners.
There were two shunts in the session with Tonio Liuzzi the first to damage his car, hitting the armco barrier before coming to a halt in the escape road for the chicane.
The other accident belonged to Michael Schumacher, who binned it at Ste Devote.
Report: The sun was baking down on the streets of Monte Carlo as the drivers geared up for the start of Thursday's opening practice session. As the lights turned green, the drivers ventured out for their installation laps before heading back into the pits, leaving a quiet track behind.
Narain Karthikeyan broke the silence, putting in a 1:38.718. The Hispania driver lowered the benchmark to a 1:27.755. Sergio Perez was the next to lead the way, followed by Pastor Maldonado. However, it was a very slow and quiet start to the session as many did not want to waste their tyre allocation on the slippery surface.
Halfway through the session it was Felipe Massa at the front with a 1:20.825, followed by Kamui Kobayashi, Maldonado, Paul di Resta, Adrian Sutil, Tonio Liuzzi, Perez and Jarno Trulli.
Mark Webber's session came to a premature conclusion due to a gearbox problem. The Aussie had completed just three installation laps.
Sutil improved to second place while Sebastian Vettel claimed third, 2.230s behind Massa. Moments later the red flags were waved, apparently because of water leaking onto the track, causing a puddle on the pit straight. Race Control: "Repairs being made to the track on the pit straight."
Five minutes later the action resumed with Lewis Hamilton improving to second place, 1.586s behind Massa. The McLaren driver closed the gap to 0.188s with Jenson Button taking third place. Hamilton's next lap saw him finally overhaul Massa by 0.446s despite coming up to traffic in the form of Heikki Kovalainen.
Fernando Alonso was the next to lead the way with a 1:17.619 and Nico Rosberg moved up to second place with Michael Schumacher taking sixth. Tonio Liuzzi became the first crasher of the morning as he took the front wing off his Hispania, coming to a stop in the escape road of the chicane.
Hamilton returned to the front with a 1:17.350 and although Alonso bettered his own time, the Ferrari driver was not able to overhaul the McLaren. Massa climbed to third place and then jumped to first, 0.034s up on Hamilton.
Vettel took over at the top with a 1:17.309, just 0.007s up on Massa. Schumacher's session came to a premature halt when he binned it at Ste Devote after braking for a slow Hispania. His team-mate Rosberg went quickest with Alonso moving up to second.
Practice One ended with Vettel at the front with a 1:16.619, edging Alonso by 0.113s. Rosberg was third.
Times
01. Sebastian Vettel Red Bull-Renault 1m16.619 25 laps
02. Fernando Alonso Ferrari 1m16.732 + 0.113 24 laps
03. Nico Rosberg Mercedes 1m17.139 + 0.520 20 laps
04. Felipe Massa Ferrari 1m17.316 + 0.697 24 laps
05. Lewis Hamilton McLaren-Mercedes 1m17.350 + 0.731 23 laps
06. Jenson Button McLaren-Mercedes 1m17.534 + 0.915 24 laps
07. Pastor Maldonado Williams-Cosworth 1m18.527 + 1.908 30 laps
08. Adrian Sutil Force India-Mercedes 1m18.578 + 1.959 24 laps
09. Vitaly Petrov Renault 1m18.733 + 2.114 16 laps
10. Michael Schumacher Mercedes 1m18.805 + 2.186 14 laps
11. Nick Heidfeld Renault 1m18.928 + 2.309 19 laps
12. Sebastien Buemi Toro Rosso-Ferrari 1m19.234 + 2.615 24 laps
13. Rubens Barrichello Williams-Cosworth 1m19.395 + 2.776 24 laps
14. Daniel Ricciardo Toro Rosso-Ferrari 1m19.463 + 2.844 25 laps
15. Kamui Kobayashi Sauber-Ferrari 1m19.768 + 3.149 25 laps
16. Sergio Perez Sauber-Ferrari 1m19.792 + 3.173 26 laps
17. Heikki Kovalainen Lotus-Renault 1m20.083 + 3.464 23 laps
18. Jarno Trulli Lotus-Renault 1m21.116 + 4.497 27 laps
19. Paul di Resta Force India-Mercedes 1m21.548 + 4.929 32 laps
20. Jerome D'Ambrosio Virgin-Cosworth 1m21.758 + 5.139 31 laps
21. Timo Glock Virgin-Cosworth 1m21.815 + 5.196 17 laps
22. Tonio Liuzzi HRT-Cosworth 1m22.840 + 6.221 13 laps
23. Narain Karthikeyan HRT-Cosworth 1m23.885 + 7.266 37 laps
24. Mark Webber Red Bull-Renault No time 3 laps
