If you haven't been watching the Vuelta a España, you should be now

A storming time trial by Giant-Alpecin's Tom Dumoulin saw him take control of the Vuelta a España leader's jersey, but can he cling on to his slender advantage for the remaining four stages?

With just a three second gap between Dumoulin and Fabio Aru (Astana), this edition of the Vuelta is set to go down to the wire, and with some relatively sedate stages between now and Madrid we could see a quite unexpected winner.

Dumoulin was very much a rank outsider for the general classification before the race started - if you were one of those to back him at odds of 1000/1 you'll be very keen to see the Maastricht-born rider dig his heels in and hold off Aru in the Italian's favoured terrain.

But it's not just the stage 17 time trial that has set the Vuelta apart as one of the most exciting Grand Tours in recent years. Coming in to the race all the talk was of the renewal of the Tour de France rivalries between Chris Froome, Vincenzo Nibali, Nairo Quintana and Alejandro Valverde.

While stage one was a neutralised damp squib, the race burst into life on stage two with controversy surrounding Nibali's expulsion from the race for holding on to his team car.

Nibaligate unfortunately overshadowed a great stage win from the ever-smiling Esteban Chaves (Orica-GreenEdge) which set up a run for the Colombian, who held the red jersey for six of the next seven stages - his run only interrupted by Dumoulin on stage five.

Grand Tour podium ceremonies are usually pretty dull affairs, with some riders barely able to muster a smirk as they pull on whichever jersey they've acquired, but Chaves beamed from ear to ear from the moment he crossed the line (and even before) and even throughout the awkward television interviews with Eurosport.

Stage 11 hit the headlines for a number of reasons - firstly for the sheer scale of the parcours, with five huge mountains in the stage starting in Androrra, and secondly for the demise of Froome's hopes of winning the race.

The Team Sky rider fell off right at the start of the stage and rode the rest of the way, over four category one ascents and one 'especial' climb, with a broken foot.

Astana reclaimed some pride after the Nibali affair on that stage, with Mikel Landa and Aru claiming first and second, putting the beaming Italian in the red jersey for the next five stages.

While the Tour de France saw a masterclass in defensive riding from Froome, the Vuelta contenders have had to hone their attacking mentalities over the challenging parcours.

Joaquim Rodriguez almost overturned a 26-second deficit to Aru by attacking to win stage 15 and wiped out the solitary remaining second that separated them the following day by punching up the final climb on a stage won by Frank Schleck (remember him?).

A slender one second gap over Aru going into the time trial was never going to be enough for Purito, who saw his hopes of winning the 2012 Giro d'Italia slip away to Ryder Hesjedal on the final time trial.

With Rodriguez losing over three minutes to Dumoulin, the Dutchman and Aru will face off over the final four stages and it's hard to predict who will come out on top.

Dumoulin has shown this year that he can climb with the best of them, with a strong showing at the Tour de Suisse and especially in the first 16 stages of this Vuelta.

Aru, though, is an out-and-out climber and if he's unable to overturn a three-second gap on a time trialler in the upcoming mountains then it would be pretty surprising.

Where Aru chooses to attack will be fascinating. With no summit finishes left in the race, stage 19's uphill finish to Avila could be his best chance of overturning the time gap. But even then the climb is not steep and Dumoulin should have no issue getting up it.

Stage 18 features a category one climb near the end, but with a 10km descent to the finish line it could be difficult for Aru to get away and stay away. The same is the case on stage 20, which features four category one climbs but another long descent to the line.

While Dumoulin could be able to match Aru in the climbs one-on-one, the real difference may come in the shape of each rider's support.

Giant-Alpecin came to the race with a team designed to help John Degenkolb win some sprints, meaning Dumoulin has essentially been a lone wolf among the stronger teams up the climbs so far.

Aru, on the other hand, has Landa to call on, as well as a team of strong climbing domestiques who, even if they cant make it to the final climb, should be able to up the pace so much in the peloton that Giant will struggle to contain it.

Whoever comes out on top in Madrid, the 2015 Vuelta will go down in history as one of the most closely contested Grand Tours ever, with the time gap set to eclipse the 13-seconds that separated Froome and Juan Jose Cobo (remember him?) in 2011 and maybe even the eight seconds between Greg LeMond and Laurent Fignon in the 1989 Tour de France.

So if you've not tuned in yet, it's not too late. Settle down in front of the live coverage on Eurosport every afternoon - usually starting around 3pm - or catch the highlights on ITV every evening before the Tour of Britain best bits.

We promise, you won't regret it.