Jenson Button put McLaren on top of the time sheets in the second practice session in Istanbul.
His best lap of 1’26.456 was just two tenths of a second slower than last year’s pole position time.
Nico Rosberg showed good pace for Mercedes, lapping within a tenth of a second of Button to go second.
Their team mates, Lewis Hamilton and Michael Schumacher, were third and fourth. Schumacher avoided damaging his car in a lurid high-speed spin after he appeared to be caught by surprise when a Force India appeared alongside him at turn 11.
Mark Webber was fifth fastest for Red Bull but team mate Sebastian Vettel missed the entire session following his crash in first practice.
Felipe Massa was sixth fastest for Ferrari. But team mate Fernando Alonso struggled after going fastest in the first session.
An hydraulic problem delayed his running to begin with, then when he returned to the track he stopped twice. First he spun at turn six, then got the car going again, only to park up on the way in to the pits. He was pushed to his garage and later re-joined the session.
Pastor Maldonado also had problems, losing control of his car twice, as he had in first practice.
The Williams driver spun at turn eight early in the session, then in the last quarter of an hour he lost the car again and went into the carrier.
Team mate Rubens Barrichello’s session came to an early end with KERS problems.
2011 Turkish Grand Prix
Image © McLaren