Sebastian Vettel and Daniel Ricciardo put new ultra-soft tyre through its paces in thrilling duel in Barcelona.

What had been a fairly uneventful session, suddenly burst into life when, less than half-an-hour before the lunch break, Daniel Ricciardo and his former teammate Sebastian Vettel headed down the pitlane to give Pirelli's new ultra-soft compound its first outing in anger.

For several laps the two traded fastest times, the four-time world champion eventually coming out on top.

As Mercedes continued with its softly, softly approach, opting to concentrate on reliability, Nico Rosberg looked on with interest, for whilst his best time is 2.057s off his countryman's pace it was set on the medium rubber. Softly, softly catchee Ferrari, it would seem.

Max Verstappen brought about the only red flag of the day, his un-liveried Toro Rosso stopping at T13 and requiring the assistance of the rescue truck.

Esteban Gutierrez was side-lined for the first ninety minutes as Haas repaired the front wing that failed yesterday. Job done, the Mexican subsequently tried a new wing that had been shipped out overnight.

As one would expect, the teams are trying lots of updates, and nowhere are these more noticeable than at Mercedes where Rosberg ran some quite aggressive looking bargeboards. With Toto Wolff having promised some "unusual" parts in the days to come, it is understood the German team is to try a new nose also.

Whilst tenth on the sheets, Fernando Alonso will be buoyed by the fact that he has completed 71 laps, though it remains to be seen how he and his team will react to the reshuffle at Honda that sees Yasuhisa Arai effectively demoted.

Following yesterday's software issues, things have improved for Renault, Jolyon Palmer completing 41 laps, whilst the Force India appears to have good pace.

With the ultra-softs having made their debut, it will be interesting to see if Rosberg will be tempted to put them through their paces, or whether Mercedes will bide its time and focus on reliability.

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