Meintjes vs. Yates -- How alive is the battle for white?

South Africa's Louis Meintjes arrives for the eighteenth stage of the Tour de France cycling race over 179.5 kilometers (111.5 miles) with start in Briancon and finish on Izoard pass, France, Thursday, July 20, 2017. AP Photo/Peter Dejong

Thursday's Tour de France Stage 18, which will finish atop the brutal Col d'Izoard, is billed as the decisive battle between race leader Chris Froome and rivals Romain Bardet, Rigoberto Uran, and Fabio Aru, but the head-to-head for the white jersey is also red hot.

UAE Team Emirates climber Louis Meintjes' exploits on Stage 17, where he took a minute-and-a-half out of Simon Yates' 4-minute-odd lead in the race for the young rider classification, adds intrigue to Thursday's already must-watch affair.

Having turned 25 this year, this is Meintjes' final opportunity to compete for the white jersey. Last year Yates' twin brother Adam edged him to the honour, while in 2015 the South African was forced to abandon the chase through illness.

All told, Yates remains the odds-on favourite to keep the white jersey, which he has worn since Stage 5, all the way to the finish in Paris -- and has probably been getting encouraging messages from his brother.

If Meintjes is going to deny him that honour, he will have to overcome three factors.

The first is history: Only once in the past 10 years has the young rider classification lead changed hands in the final week.

That was back in 2011 when Estonia's Rein Taaramäe claimed the white jersey from Rigoberto Uran (currently running joint-second in this year's GC standings) on Stage 18, before Pierre Rolland dramatically took it off Taaramäe the very next day.

Frenchman Rolland, riding in support of Uran for Cannondale-Drapac this year, won that year's Stage 19 atop the iconic Alpe d'Huez to overhaul Taaramäe, and it will take as defining a performance from Meintjes if he's to do so this time around.

Secondly, the present is also not in the South African's favour. Until Wednesday's stage, Meintjes and Yates had been pretty much inseparable on the road in amongst the GC favourites.

They are also 2-2 when it comes to who has beaten whom in the high mountain stages so far. However, the Englishman arguably hit the knockout blow in the first of those -- Stage 9 to Chambery -- when he put 2 minutes 17 seconds into Meintjes.

Yates also has four-time top 10 Tour finisher Roman Kreuziger, his road captain, in support. Meintjes' support cast -- Diego Ulissi and Darwin Atapuma -- don't have that pedigree.

Finally, there's the future. Should Meintjes repeat Wednesday's trick and gain the ascendancy on Yates on the decisive 14.7km climb up the Izoard, then he may have to take risks -- not yet in his riding make-up -- to maximise his advantage.

That is because an individual time trial (ITT) looms on Saturday and the Orica-Scott rider will likely claw some time back there.

Much like the opening stage of Le Tour, which was a 14km-long ITT in Düsseldorf (Germany), Saturday's in Marseille is also short at 22.5km and, crucially, flat.

Neither Meintjes nor Yates would have risked their Tours when the rain fell on the opening day, but it is a fact that the Englishman finished a significant 35 seconds ahead of the South African and will expect to achieve a similar performance.

Of course, that doesn't take into account how much these two high-mountain stages will have taken out of either's legs -- always a significant factor in the final week during which minutes can easily be lost between riders.

Ultimately, the race for the white jersey has been one of the more intriguing subplots of this year's Tour de France, not least because Meintjes and Yates have largely been in the mix with the overall favourites. A final twist to their battle would no doubt add to the ever-present drama.