Alonso fastest in practice 2 - Monaco

Hamilton had been extremely fast in the first part of the session, producing a string of consistent mid-1:16 laps after usurping early pacesetter Robert Kubica with an hour to go.

The Briton lost the lead to Alonso 20 minutes later, as the Spaniard set a 1:16.211 - 0.085 seconds quicker than his teammate.

Hamilton returned to the track shortly afterwards, only to lose control under braking for Sainte Devote as he started his flying lap. The McLaren slewed into the outside barrier, causing significant front end damage.

The incident was one of several crashes during an eventful afternoon.

Five minutes before Hamilton hit the Sainte Devote wall, Super Aguri's Anthony Davidson had suffered a very similar accident, bringing his session to end.

Heikki Kovalainen was more fortunate when he carried too much speed into the same corner early on - diverting his Renault into the escape road and rejoining with minimal drama.

David Coulthard spun his Red Bull on the approach to the Grand Hotel hairpin, making light contact with the barriers. He was able to bring the slightly damaged car back to the pits for repairs.

Then in the final seconds of the session, Ralf Schumacher put his Toyota into the wall at the second part of the Swimming Pool, leaving him 20th on the timesheets at the end of the day.

The only incident that required a red flag was Adrian Sutil's late crash at Portier. The German made heavy contact with the wall on the entry to the corner with 20 minutes to go, but the debris was quickly cleared and the session resumed just four minutes later.

Alonso improved his time to a 1:15.940 towards the end of practice, putting him 0.275 seconds clear of second-placed Kimi Raikkonen at the chequered flag.

Hamilton's early lap was sufficient for third despite his accident, while late improvements from long-time Monaco specialists Jarno Trulli and Giancarlo Fisichella put the two Italians fourth and fifth, ahead of Felipe Massa.

Robert Kubica, Nico Rosberg, and the two Red Bulls completed the top ten.

Nick Heidfeld was only 14th after fuel pressure problems, while the two Toro Rossos again produced top six times early on, but faded to 16th and 18th by the end of the session.

Pos  Driver        Team                    Time              Laps
 1.  Alonso        McLaren-Mercedes   (B)  1:15.940            40  
 2.  Raikkonen     Ferrari            (B)  1:16.215  + 0.275   43  
 3.  Hamilton      McLaren-Mercedes   (B)  1:16.296  + 0.356   19  
 4.  Trulli        Toyota             (B)  1:16.354  + 0.414   39  
 5.  Fisichella    Renault            (B)  1:16.753  + 0.813   41  
 6.  Massa         Ferrari            (B)  1:16.784  + 0.844   37  
 7.  Kubica        BMW Sauber         (B)  1:16.848  + 0.908   48  
 8.  Rosberg       Williams-Toyota    (B)  1:16.852  + 0.912   34  
 9.  Webber        Red Bull-Renault   (B)  1:17.292  + 1.352   16  
10.  Coulthard     Red Bull-Renault   (B)  1:17.414  + 1.474   16  
11.  Barrichello   Honda              (B)  1:17.449  + 1.509   40  
12.  Button        Honda              (B)  1:17.457  + 1.517   45  
13.  Sato          Super Aguri-Honda  (B)  1:17.459  + 1.519   47  
14.  Heidfeld      BMW Sauber         (B)  1:17.486  + 1.546   43  
15.  Wurz          Williams-Toyota    (B)  1:17.516  + 1.576   34  
16.  Liuzzi        Toro Rosso-Ferrari (B)  1:17.898  + 1.958   42  
17.  Kovalainen    Renault            (B)  1:18.086  + 2.146   41  
18.  Speed         Toro Rosso-Ferrari (B)  1:18.233  + 2.293   40  
19.  Davidson      Super Aguri-Honda  (B)  1:18.328  + 2.388   25  
20.  R.Schumacher  Toyota             (B)  1:18.662  + 2.722   38  
21.  Albers        Spyker-Ferrari     (B)  1:18.820  + 2.880   35  
22.  Sutil         Spyker-Ferrari     (B)  1:19.358  + 3.418   29