Alonso puts Renault on top at Jerez

Alonso, who was quickest for three consecutive days at Valencia last week, continued to show the new Renault R26's impressive pace, posting a best lap of 1:16.956.

But the World Champion was followed closely by Button in the Honda RA106 and Juan Pablo Montoya, who showed improved pace in the McLaren MP4-21.

Both Button, Alonso and Montoya set the quickest time on short stints close to the end of the session.

Montoya only tested in the afternoon as he waited for the revamped Mercedes engine to arrive and be fitted to his car. The Colombian worked alongside test driver Pedro de la Rosa, the busiest man today and the only driver in a V10-engined car.

Rubens Barrichello was fifth quickest in the second Honda, the Brazilian losing a lot of time after his car stopped with problems at the end of the pitlane. His team spent several hours working on the car before Barrichello was able to return to action.

BMW's Nick Heidfeld and Jacques Villeneuve showed promising pace in the new F1.06, both men working on brake and tyre testing.

Australian Mark Webber was only eighth quickest in the new Williams, but the new FW28 car and the Cosworth engine have proved very consistent at the Spanish circuit.

Webber's teammate Nico Rosberg, testing the second FW28 chassis, did not enjoy a good day and could only cover 29 laps after his car stopped on track in the early afternoon.

Toyota's Jarno Trulli and Ralf Schumacher were 10th and 11th quickest respectively, the Italian causing one of five red flags on the day when he went off track late in the session.

Tiago Monteiro was the only Midland driver to take to the track today, the Portuguese at the wheel of the hybrid EJ15B. Monteiro, who did tyre testing in the afternoon, will test the new MF16 car tomorrow for the first time.

Today's times:

Pos  Driver        Team                      Time      Laps
 1.  Alonso        Renault              (M)  1:16.956   90
 2.  Button        Honda                (M)  1:17.114   58
 3.  Montoya       McLaren-Mercedes     (M)  1:17.273   53
 4.  de la Rosa    McLaren-Mercedes     (M)  1:17.425  109
 5.  Barrichello   Honda                (M)  1:17.492   60
 6.  Heidfeld      BMW-Sauber           (M)  1:17.588  116
 7.  Villeneuve    BMW-Sauber           (M)  1:18.069   91
 8.  Webber        Williams-Cosworth    (B)  1:18.281   86
 9.  Kovalainen    Renault              (M)  1:18.938   77
10.  Trulli        Toyota               (B)  1:19.430  103
11.  R.Schumacher  Toyota               (B)  1:19.681   84
12.  Rosberg       Williams-Cosworth    (B)  1:19.965   29
13.  Monteiro      MF1-Toyota           (B)  1:21.911   29

All Timing Unofficial