The BAR-Honda driver proved to be a quick learner at the new Istanbul Otodrom, setting the second fastest time in both this morning’s practice sessions as more experienced drivers found the going tough.

In both sessions Button held top spot going into the final seconds only for a McLaren to pip him to the honour.

Montoya deposed him in first practice before Raikkonen took the fastest time in the second.

Raikkonen, whose McLaren team has dominated in Turkey so far, set a best lap of one minute 26.120 seconds in the final session to set the pace.

Button’s best effort was within half a second and put him faster than world championship leader Fernando Alonso, who was third for Renault.

That has raised hopes of a season’s best for Button, whose top result so far in 2005 has been third.

Montoya emphasised McLaren’s strength by taking fourth with Giancarlo Fisichella in fifth showing Renault are also a force to be reckoned with.

Takuma Sato was sixth for BAR with Williams’ Mark Webber seventh and Toyota’s Ralf Schumacher eighth. David Coulthard was ninth for Red Bull with Michael Schumacher struggling again down in 14th.

Midway through the session Webber became the latest driver to come a cropper on the new circuit, suffering a right-rear puncture at turn seven which pitched him into the gravel.

Unusually, the all-conquering Ferrari team were suffering more than any of their rivals.

An error-strewn day yesterday contributed to a lack of speed from both Michael Schumacher and Rubens Barrichello and practice this morning showed no improvement.

Schumacher, who admitted he misjudged the challenge posed by the new circuit, spun yesterday and followed that up with more errors. Barrichello was also in the wars and went off track as well.

Even on-form drivers were pushing beyond the limit though and Raikkonen, fresh from his victory in Hungary three weeks ago, ran wide at turn eight.