Was it an under-the-radar lap from Kimi Raikkonen during this week's Barcelona testing that prompted Mercedes to fear that Ferrari is very close? Jonathan Noble investigates.

By: Jonathan Noble, Formula 1 Editor

Was it an under-the-radar lap from Kimi Raikkonen during this week's Barcelona testing that prompted Mercedes to fear that Ferrari is very close? Jonathan Noble investigates.

Nico Rosberg surprised a few people at the end of Formula 1 testing with his claim that his Mercedes team did not know if it was behind or ahead of its Italian rival.

For the message speaking to teams up and down the pit lane – judging by the remarkable efficiency by which Mercedes had completed nearly 20 grands prix distances over the two weeks – was that the Silver Arrows were in a league of their own.

But while test two at Barcelona had begun surrounded by doubts about Ferrari's pace and reliability, by the end of it there emerged some cautious optimism from within the Maranello outfit itself about where things were at.

Sebastian Vettel is not a man to let excitement get the better of him, but even he reckoned that Ferrari was closer - it just did not know how much closer.

“Obviously we’ve tried to close the gap, it’s been quite big across the last year,” Vettel said as he rounded off testing.

“I think we’ve done a good job across the last season to get a little bit closer and now I think the new car gives us the chance to close the gap. How much? We need to be a bit more patient for a few weeks at least.”

Benchmarking times

Naturally, it is always hard to draw definitive conclusions from testing, because there are multiple factors that come in to play when best lap times are delivered.

On a base level, there are the tyre compounds and fuel loads, but nowadays there are also engine settings to contend with, allied with the fact Barcelona is invariably quicker in the mornings than it is in the afternoons when the wind picks up.

The only factor that we can know for sure is on what tyre compound each driver set his quickest time, which will then allow us to get a slightly clearer look at where things stand.

So to get a better judgement, let's aggregate the best times of the week to give us a theoretical time that each car could achieve.

Pirelli's estimates of the time difference between the compounds was that there was an average 0.65 seconds difference between the ultrasoft and the supersoft, a 0.5 seconds difference between the supersoft and the soft, and a 0.95 seconds difference between the soft and medium.

Pirelli was quite eager to point out that the challenging Barcelona track was not ideal for the ultrasoft and supersoft, so we will base our calculations around a theoretical or real soft compound time.

Using the fastest times of the test, we can then add 1.15 seconds to the ultrasoft times, and 0.5 seconds to the supersoft times to balance things out.

This then gives us a final top ten ranking of the week that stands like this:

Pos. Driver Team Time
1  Nico Rosberg  Mercedes 1m23.022s
2  Felipe Massa  Williams 1m23.193s
3  Sebastian Vettel  Ferrari 1m23.352s
4  Lewis Hamilton  Mercedes 1m23.622s
5  Kimi Raikkonen  Ferrari 1m23.915s
6  Carlos Sainz  Toro Rosso 1m24.284
7  Valtteri Bottas  Williams 1m24.379s
8  Nico Hulkenberg  Force India 1m24.401s
9  Daniel Ricciardo  Red Bull 1m24.427s
10  Max Verstappen  Toro Rosso 1m24.532s

That would appear to show that while Ferrari and Williams have closed the gap to the front (pending fuel load variability, of course), but Mercedes still appears to have a decent edge.

The hidden lap

But finding answers in F1 is all about the details, and it is by digging a bit deeper into what the teams have done that throws up a fascinating insight in to the relative pace of Ferrari.

For, while Kimi Raikkonen's best ultra soft lap on Thursday will go down as the best lap overall of the week, it is the not the lap that shows us whatFerrari is fully capable of.

Just before he left the track on Thursday night, Ferrari team principal Maurizio Arrivabene was instead raving about another lap that Raikkonen had done that same day.

“Kimi got his best time with ultrasoft tyres [1m22.765s] but the lap that impressed me the most was one with the softs [1m23.009s],” Arrivabene told Motorsport.com.

“We know that when he used the softer compound [ultrasoft] he complained about the presence of a strong wind on the track, and probably did not use all the speed potential in the tyres.”

The message was clear. Raikkonen's best ultrasoft lap may have been good enough for the fastest time overall, but it wasn't actually anywhere near whatFerrari could have delivered.

So instead, if we compare Raikkonen's best soft lap effort with Rosberg's, we end up with the Finn edging out the Mercedes by 0.013 seconds.

Of course, endless variabilities (fuel loads, engine settings, test programme, track conditions) means that the pace change could put either car ahead by a margin, but it means there is definitely no guarantee Mercedes is in a complete class of its own either.

That Raikkonen lap may have prompted Rosberg's comments on Friday night; but equally Ferrari is not taking anything for granted.

“We have not seen all the resources of Mercedes,” added Arrivabene. “So it is still early to draw conclusions. We must always keep our feet on the ground and continue in our work programme.

"Having said that, we are happy with the feedback we have had from the track.”

There will be more number crunching over the next few days, but it will not be until Saturday afternoon in Melbourne – when everyone is on the same fuel, same tyres and same track – that we will know for definite whether it is game on for the 2016 F1 title battle or just another year of Mercedes dominance.

Additional reporting by Roberto Chinchero

Gallery: Analysis: Did an unnoticed Raikkonen lap reveal Ferrari's true pace?