On Thursday the final four days of pre-season testing before Melbourne get underway at Bahrain’s Sakhir International Circuit.

For some the aim is to refine and continue development of the cars, for others the simple task of completing decent mileage ahead of the opening race remains a big challenge.

With that in mind here’s the key things all F1 fans should look out for this week in the desert.

First is a continued domination of the lap times and lap count by Mercedes powered teams.

Of course by having four teams, the British-based German marque will naturally have the edge on the others, particularly Ferrari, but so far the story of testing has been the likes of Mercedes, McLaren and Williams achieving upwards of 100 laps on an increasingly daily basis.

This means that the reliability of the new unit is perhaps the best of the three engine suppliers, however, as Force India and Mercedes have shown it’s certainly not bulletproof.

The fact remains also that only Kimi Raikkonen’s Ferrari has been able to knock the Mercedes teams off the top of the timings in testing so far.

Of course that doesn't particularly matter at this stage but with Mercedes, McLaren, Williams and Force India often at least in the top six most days surely it does mean something.

Next is Ferrari. The Scuderia has always been the team in the middle of the sea of German-ness during the tests so far.

Yet despite that they have yet to let anything out of the bag in terms of their pace.

Reliability – which has become the key aspect to this year’s preseason – again hasn’t been perfect but both Raikkonen and Fernando Alonso have consistently tallied up good mileage on a daily basis.

So really the story for the final test is whether they will push the F14-T a little harder and also complete an important race simulation which so far only Nico Rosberg has done.

The final test, I believe, could be a key turning point for Lotus. The E22 has already begun to show signs of better coping with the troublesome Renault power unit and the radical ‘twin-tusk’ nose does appear to have an advantage over the other designs seen so far.

After a topsy-turvy first week’s testing last week I also feel the Enstone-based team will have a much better understanding of the new car and will be able to complete good mileage and possibly assert themselves as the leading French powered outfit heading to Melbourne.

Of course that title would come at the expense of world champions Red Bull who, let’s be honest, have had an abysmal preseason so far.

Only once over the eight days so far has the RB10 managed to complete over 50 laps in a single day while new boy Daniel Ricciardo has failed to even reach 30.

There is no doubt the trouble Red Bull are in is the biggest story of these past few weeks as the tight packaging of Adrian Newey’s latest creation allied to the overheating tendencies of Renault’s ERS units have created a problem so big some believe it could take months to sort.

Certainly what fans should watch out for this week is the team simply being able to complete some decent long runs, I would go so far as to say, as we understand it currently, the RB10 is unraceable and incapable of completing a full race distance, certainly talk of challenging for another world championship is the furthest thing from Sebastian Vettel and his team’s minds at this time.

That unraceable point stretches to a few teams, notably Marussia and Caterham.

Though the Norfolk-based team has completed the most mileage of any Renault powered team so far, this has been done with the engine turned down, such is the lack of pace driver Kamui Kobayashi claimed his team would be better off taking it’s GP2 car to Melbourne.

Meanwhile Marussia will be hoping to recover from a blown engine and becoming the first team I can think of to suffer from a computer virus which all but left the team stranded in the garage.

With the Ferrari motor in the back it is not beyond the realms of possibility the team can make up for some lost time so therefore watch out for some high lap totals from Max Chilton and Jules Bianchi this week even if the lap-times won’t be brilliant.

For the major midfield teams the need to ‘sandbag’ usually doesn’t exist in testing certainly the order from last year appears to have been jumbled with Force India and Williams in particular looking stronger with Sauber and Toro Rosso a little bit behind.

I am expecting a jump forward in lap-time, perhaps not to the 1:33 level set by Rosberg last week but that won’t be important, watching the times on stints over 15 laps will be the most important. It promises to be a fascinating four days.

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