The Belgian Grand Prix could produce an intriguing match up between Mercedes and Ferrari

The notoriously fickle Spa weather stayed dry throughout the second practice session, revealing a potential strategic conundrum based around the tyre choice of super-soft/soft/medium.

On single lap pace, on super-softs, Ferrari had a small edge over Mercedes – Kimi Räikkönen went fastest, a couple of tenths faster than Lewis Hamilton. Sebastian Vettel suffered a moment on the crucial new-tyre lap, while Valtteri Bottas – taking a grid penalty for an engine change – concentrated on long runs. Max Verstappen’s Red Bull was around 0.5sec adrift of Hamilton, with Daniel Ricciardo playing catch up after missing most of Free Practice 1.

This picture will likely change a little through the engine mode effect of Q3, but essentially we can expect a close pole contest featuring both Mercedes and Ferrari.

It is in the long runs where the intrigue is. The super-softs are blistering the left-rears after only six or seven laps. Ricciardo and Verstappen suffered the most with this, but Räikkönen and Hamilton weren’t far behind. This makes a one-stop particularly problematic over a 44-lap race – especially as the hardest tyre (the medium) isn’t really fast enough, beginning around 1.2/1.3sec slower than the soft.

Vettel was the only driver to do a decent run on mediums, at almost 1sec faster than Hamilton. But…

In looking at the feasibility of a one-stop, it looks like the soft may not be quite durable enough to make up for the shortfall of laps the super will impose. The medium is plenty durable enough, but not fast enough. So a two-stop looks like being the default strategy. But if someone can break one of those soft or medium codes and the others can’t, he will save himself the 25sec of a pitstop and just might be able to pull off a spectacular result.

Qualifying in Q2 on the softs is slightly risky even for the fast cars, as they are around 1.1sec slower over a lap than the super-softs. Besides, it still doesn’t really get you out of the strategic conundrum, in that their range probably isn’t long enough to allow the fitment of supers for a short final stint. Or is it?

Is that the high-risk route to an against-the-odds victory?

It should be emphasised that these patterns played out over a dry track surface of 26/27deg C. The forecast for Sunday is cooler and damper. Spa generally responds to a tyre with a hard compound but a high working temperature range. The super-soft has a low working range. The soft has a higher working range (ie better for Spa with regards both to compound and working range) whereas the medium has a harder compound (good) but a lower working range (bad). Hence the soft probably being the favoured tyre. At cooler track temperatures, the super-soft’s range might not be quite so bad – but not by enough to change the fundamental strategic challenge.

So how did the Ferrari and Mercedes compare on the soft – the tyre likely to be used for the crucial part of the race? Advantage Mercedes. Bottas did a 12-lap run, nine of which were representative and averaged around 1min 48.7sec. Raikkonen did a five-lap run on them, averaging around 1min 49.0sec. Vettel was the only driver to do a decent run on mediums, at almost 1sec faster than Hamilton. But it’s difficult to see how that helps him. On the short super-soft runs, Hamilton shaded Räikkönen by around 0.1sec, but with a first-stint fuel load (as opposed to Räikkönen’s second-stint fuel load), so in reality the gap was bigger than it appeared.

On the evidence of FP2, the Ferrari may have the edge over a lap of Spa, the Merc over a sequence of them – and on a track where passing is relatively easy. But there’s a huge strategic jeopardy that could make all of that irrelevant. 

Read more from Mark Hughes