Fernando Alonso stole the limelight from more expected frontrunners as the practice phase of this weekend's Monaco Grand Prix came to an end, posting a late 1min 15.164secs to keep Jenson Button from the top of the timesheets.
Top spot changed hands with some regularity towards the end of the hour but, unlike other races on more conventional circuits, the big guns continued to feature, with Brawn, McLaren and Ferrari all putting at least one driver in P1.
Alonso, running without KERS this weekend, moved to the front with a couple of minutes remaining, with Button lagging 0.069secs behind the Renault as the chequered flag fell. The remainder of the top five, meanwhile, was within a couple of tenths, with Heikki Kovalainen, Rubens Barrichello and Felipe Massa next up.
Ferrari and McLaren continued to hint at better form this weekend, with Kimi Raikkonen and Lewis Hamilton both among the pacesetters, the Briton having been the man to beat until the latter stages, when he appeared to allow others centre stage. Nevertheless, he finished the hour in seventh spot, and should be a threat for a solid qualifying position.
Red Bull, by contrast, appeared to be keeping its powder dry, with Sebastian Vettel only eighth, and Mark Webber tenth, and half a second off the pace. The pair sandwiched regular FP3 pacesetter Nico Rosberg, with the second Williams, of Kazuki Nakajima, in eleventh spot.
The Japanese driver was the last of those within a second of Alonso's time, with Adrian Sutil only just missing the bracket as he lapped 1.064secs shy in the best of the Force Indias. The Silverstone team showed promise with Giancarlo Fisichella 14th, despite one lairy moment at the seafront chicane, but may have been running lighter than its rivals as it moved away from the lower reaches of the table.
Force India's usual positions were filled by 'unlikely lads' Toyota and BMW Sauber, which failed to break out of the bottom four with any of its drivers. Nelson Piquet Jr and Sebastien Buemi filled the space between Fisichella and the stragglers.