F1: Sebastian Vettel fastest during practice for Belgian Grand Prix - but Pirelli tyre issues resurface

Lewis Hamilton over a seconds off the pace in his Mercedes

Pirelli suffered its first tyre issue since the blowouts that caused a storm over the British Grand Prix weekend.

A series of incidents, notably during the race itself at Silverstone, forced Pirelli into a redesign of its tyres for the subsequent grands prix that followed in Germany and Hungary last month.

From Hungary in particular, the Italian manufacturer adopted a design that incorporated the structure of last year's tyres with this year's compounds.

Prior to this weekend's race in Belgium, Pirelli motorsport director Paul Hembery conceded the high-speed nature of the Spa-Francorchamps circuit would prove the acid test of the latest construction due to the strain and heavy loads involved.

During the second practice session, run in the dry as opposed to the mixed conditions that prevailed throughout the opening 90 minutes, reigning world champion Sebastian Vettel was the man to suffer.

It was nothing as spectacular as what occurred during the British race as on this occasion Vettel's right rear appeared to delaminate on the back of sustaining a puncture, with Pirelli looking into the reason behind it.

The incident, however, did not stop Vettel from topping the timesheet with a lap of one minute 49.331secs, six seconds faster than that set by Ferrari's Fernando Alonso in the first session, an indicator as to how much the conditions affected matters early on.

Vettel ultimately spearheaded a Red Bull one-two, with team-mate Mark Webber 0.059secs adrift, and with the duo head and shoulders ahead of the remainder of the field.

Lotus' Romain Grosjean was third fastest, but with the Frenchman just over eight tenths of a second behind Vettel.

Team-mate Kimi Raikkonen, behind the wheel of his car after skipping media activities on Thursday through illness, was sixth quickest and a second back.

Sandwiched in between the duo were Ferrari's Felipe Massa and Jean-Eric Vergne in his Toro Rosso, the former with something to prove over the second half of the season with his seat in doubt.

Alonso was seventh overall, followed by McLaren's Sergio Perez and Mercedes' Nico Rosberg, with Paul Di Resta in his Force India completing the top 10, the Scot 1.280secs back.

As for his fellow Britons, Lewis Hamilton was down in 12th in his Mercedes and 1.420secs adrift, while McLaren's Jenson Button was a further four tenths of a second further back in 15th.

Max Chilton brought up the rear in his Marussia, the 22-year-old finishing five seconds off of Vettel's pace.

Aside from Vettel, the only other incident of note saw Giedo van der Garde crash his Caterham at Stavelot.

PA