Lewis Hamilton edged out Mercedes teammate Nico Rosberg at the top of the timesheets in first practice for the Monaco Grand Prix on Thursday as the new ultra-soft tire made its debut.
Pirelli announced over the winter that it had developed a fifth dry compound for 2016 that is bespoke for street circuits such as Monaco.
The purple-ringed tire has only featured in testing so far this year, but made its official grand prix weekend debut in a truncated first practice in Monaco.
Hamilton and Rosberg immediately put the ultra-soft tire to good use, heading out early for a flurry of quick laps that were already faster than the pole position time from 2015.
Hamilton ultimately won the battle, with his lap of 1:15.537 being enough for P1 by one-tenth of a second as Mercedes began its fightback from a double DNF in Spain.
The session was interrupted by four virtual safety car periods. Felipe Massa was responsible for the first after clouting the barrier at Ste Devote, before Esteban Gutierrez and Jolyon Palmer both stopped on track in the final 30 minutes of the running.
A final VSC was throw with five minutes remaining in the session after a drain cover broke free at Turn 1, causing Rosberg to suffer a left-rear puncture and then leaving Jenson Button’s McLaren with significant front wing damage. The session was then red flagged, bringing an early end to proceedings
Nevertheless, Mercedes eased clear at the top of the standings, with Ferrari’s Sebastian Vettel finishing as the best of the rest in third place, four-tenths of a second down on Hamilton.
Daniel Ricciardo put his newly-updated Renault power unit to good use to finish the session fourth-fastest for Red Bull, beating teammate Max Verstappen who continued his good form after his victory in Spain to end the session fifth.
Daniil Kvyat impressed for Toro Rosso to finish FP1 in sixth place, narrowly behind the man who replaced him at Red Bull. Nico Hulkenberg and Sergio Perez ended the session seventh and eighth respectively for Force India, while Kimi Raikkonen and Carlos Sainz Jr. rounded out the top 10.