Barrichello leads Button in first practice

The Brazilian got ahead of Button right at the end of a session that the Briton had largely commanded.

Mark Webber and Sebastian Vettel took an encouraging third and fifth for Red Bull, split by Fernando Alonso's Renault.

The session was halted for ten minutes at half-distance - and with uncomfortable irony the red flag was caused by Renault's number two driver crashing at Turn 17, just as Nelson Piquet had in last year's now infamous choreographed mid-race crash.

Romain Grosjean's incident was less damaging, the Frenchman's Renault brushing the wall with its rear end as it spun under acceleration and nosed into the barriers on the other side of the road.

The stoppage came just as Button moved ahead of Webber to take the top spot, and that's where the championship leader remained until the final few minutes of the session.

Heikki Kovalainen (McLaren) briefly usurped Button at the hour mark, the Finn having earlier caught a spin before his McLaren could make contact with the barriers.

But Button was soon back in front, and it was only in the last runs of the session that rivals pushed him back down the order, with Barrichello taking the top spot with a 1m50.179s.

Button was pushed right back to fifth, before reclaiming second with a time 0.177s down on Barrichello as the flag waved to end the session.

Webber ended up third, despite a late trip down an escape road, ahead of Alonso, Vettel and the two McLarens.

The slight adjustments to the track - which has been tightened slightly on some bends - had a noticeable effect on the lap times, which were five seconds slower than in the same session last year.

The crowd also had its first look at Formula 1 cars lapping Singapore in relative daylight, as with practice commencing an hour earlier than it had in the 2008 event, the first few runs took place before darkness had fallen.

Pos  Driver       Team                       Time              Laps
 1.  Barrichello  Brawn-Mercedes        (B)  1:50.179            19
 2.  Button       Brawn-Mercedes        (B)  1:50.356  + 0.177   22
 3.  Webber       Red Bull-Renault      (B)  1:50.416  + 0.237   21
 4.  Alonso       Renault               (B)  1:50.567  + 0.388   16
 5.  Vettel       Red Bull-Renault      (B)  1:50.614  + 0.435   16
 6.  Kovalainen   McLaren-Mercedes      (B)  1:50.699  + 0.520   21
 7.  Hamilton     McLaren-Mercedes      (B)  1:50.715  + 0.536   17
 8.  Kubica       BMW-Sauber            (B)  1:50.815  + 0.636   15
 9.  Raikkonen    Ferrari               (B)  1:50.865  + 0.686   ù.
10.  Nakajima     Williams-Toyota       (B)  1:51.089  + 0.910   25
11.  Rosberg      Williams-Toyota       (B)  1:51.427  + 1.248   23
12.  Sutil        Force India-Mercedes  (B)  1:51.544  + 1.365   14
13.  Buemi        Toro Rosso-Ferrari    (B)  1:51.643  + 1.464   28
14.  Heidfeld     BMW-Sauber            (B)  1:51.656  + 1.477   15
15.  Glock        Toyota                (B)  1:52.083  + 1.904   20
16.  Trulli       Toyota                (B)  1:52.135  + 1.956   20
17.  Fisichella   Ferrari               (B)  1:52.390  + 2.211   24
18.  Liuzzi       Force India-Mercedes  (B)  1:52.905  + 2.726   23
19.  Alguersuari  Toro Rosso-Ferrari    (B)  1:53.232  + 3.053   25
20.  Grosjean     Renault               (B)  1:53.458  + 3.279    9

All Timing Unofficial