Barrichello stays top at lunchtime in Jerez
The Brazilian's lap, clocked less than an hour into the day, was set on a run of over five laps, suggesting that the team is yet to fully test the potential of the BGP001 on a single qualifying flyer. Nevertheless, the time is the fastest recorded by a 2009-spec machine, beating the previous best of 1m19.055s set by Sebastian Vettel at the beginning of the month. Barrichello now hands over to team-mate Button who will complete the rest of the day's running.
Elsewhere in the pitlane, Fernando Alonso had a trouble-free start to his final day on-track, while former team-mate Lewis Hamilton got McLaren's running underway in the MP4-24. Nico Rosberg was also on duty for Williams, taking over from test driver Nico Hülkenberg.
Testing continues in Jerez this afternoon, so check back later today for the final times and a full report on the day's running.
Unofficial morning times from Jerez:
1. Rubens Barrichello (Brawn-Mercedes) – 1:18.398, 19 laps
2. Fernando Alonso (Renault) – 1:19.334, 42 laps
3. Lewis Hamilton (McLaren-Mercedes) – 1:19.629, 28 laps
4. Nico Rosberg (Williams-Toyota) – 1:19.783, 30 laps