Mark Webber's retirement from Formula One after this season leaves a space in the Red Bull team, a coveted spare seat for the triple world championship-winning outfit. Although the drive will no doubt be a number two position to favourite Sebastian Vettel, it's a role that could come into its own if the German decides to move on when his contract is up at the end of 2014.

There are a number of potential drivers that could fill this role, but the two most prominent names in the frame are the Toro Rosso pairing of Daniel Ricciardo and Jean-Éric Vergne. The sister outfit to Red Bull Racing, Toro Rosso have been a proving ground for talent that might one day make its way into the main team - following in Vettel's footsteps after his promotion in 2008.

Ricciardo and Vergne have a lot to prove if they are going to make it to the big time, and there's no guarantee they'll get the promotion. But if Red Bull do want to pluck one of these two from their talent pool, who might be the better option?

Jean-Éric Vergne

Vergne is definitely the quieter half of the Toro Rosso duo, but just recently we have seen more from the Frenchman - he's developing a public personality and delivering results on track, key things for ultimate success in Formula One. Unfortunately for the Frenchman, in the last two races - just as his teammate has started to shine - he has had some significant bad luck.

At Silverstone, he followed Ricciardo to an unusually high qualifying spot. Pulling out a one-lap special on a Saturday afternoon has not been Vergne's strong point. A limitation that has to count against him if he is to be considered for the second seat at Red Bull is his ability to draw the most out of the car during qualifying. Particularly if you are sitting alongside a man who has ring fenced pole position as his very own, Sebastian Vettel. Failure to deliver just won't cut it.

Nevertheless, for the British Grand Prix, Vergne found himself 13th after the qualifying sessions ended. Not the top ten performance of Ricciardo, but a strong outing for Jean-Éric. In Germany, he was 16th, which is heading in the wrong direction again, but it is in the races that the real trouble occurred. Vergne was one of the four drivers affected by the tyre blowouts at Silverstone, and a hydraulics problem brought his German Grand Prix to an abrupt end this past weekend.

But despite the difficulties he has had this year, he is managing to hold his own against teammate Ricciardo. Statistics wise, in 2013, they are almost neck and neck come race day. Both have finished in the points three times this year, but Vergne edges it with a high sixth place which leaves him ahead in the driver's championship standings.

The Frenchman is quiet, hard-working, eager to please with plenty to learn but knowledge of all the tracks. Ricciardo may have half a season of F1 experience over him, but at this point they have both driven all the circuits enough times to know their way around. Luck hasn't been kind to Jean-Éric so far this year but he is battling hard and taking the fight to the guy in the opposing garage. That's the kind of spirit he'd need against Vettel and any possible replacements of the champion in the future.

Daniel Ricciardo

Daniel Ricciardo has been a member of the F1 paddock for three seasons, and has made a significant impression already. In fact, he raised eyebrows on his very first outing in an F1 car, participating in a Young Driver Test for Red Bull back in 2009. Over the course of the three days, he put in several strong performances and finished the final day with the fastest time. That was enough to grant him a test drive for Toro Rosso.

Known as a driver that comes with a big smile, there was a brief dip in his optimism when he was loaned out to struggling backmarker team HRT for the second half of the 2011 season. Although participating in eleven race weekends and learning his way around those tracks in F1 machinery was great for his experience, there were a lot of negatives to go with it. Driving at the back of the field, jumping out the way when the blue flags are waved, and ultimately never finishing higher than 18th, all this is difficult for a passionate and ambitious young driver to deal with.

Thankfully for Ricciardo, a Toro Rosso race seat was the reward for his efforts, and he's been driving for the Italian squad for one and a half seasons now. Although performances have been something of a rollercoaster, there have been numerous determined drives across the years. In 2012, Daniel finished in the top ten six times, and he is halfway to that achievement already this year.

Last year, his first alongside Jean-Éric Vergne, he qualified ahead 16 times to the Frenchman's 4. On race day, Vergne clawed some positions back but it was still Daniel ahead 12 times to 8. This season he still has the edge, but things are a lot closer, particularly come Sunday. The last two qualifying sessions, at Silverstone and the Nürburgring, have seen Ricciardo qualify in sixth place, apparently unfazed to be starring in the top ten shootout. In Britain, he kept the car in the top ten during the race, but in Germany he struggled with significant tyre wear and labelled it a "dull" event.

So what can we learn from all this? Fast on his day, but perhaps struggling for consistency, Ricciardo has the people skills to fit in at Red Bull and plenty of time to hone his race craft. Would he be contented as a number two driver though? Or would the tendency to get frustrated creep in and mess up his performance?

The choice is theirs

Red Bull haven't said anything about who they are considering for the second seat in 2014, but if they are choosing between these two, it's going to be a very tough decision. You've got Ricciardo's winning personality but temperamental race results, against Vergne's quiet aptitude in the race but disappointing pace over one lap.

And as we discussed in this week's show, the team also have to consider how the driver who gets left behind will react. Can they continue in their role happily watching their friend and colleague promoted ahead of them? I get the feeling Vergne would be able to deal with the missed opportunity better than Ricciardo, and I also think Daniel is the better choice for promotion.

He may not have developed his Sunday racecraft to perfection yet, but if he has a year alongside Sebastian Vettel in the top car, that's plenty of time to improve and hone his pace. Inevitably there would be a vast amount of pressure on whoever made the cut and I feel like Ricciardo could deal with that better than his Toro Rosso counterpart.

Image credit: Peter Fox / Getty