MENDE - The prospect of a maiden yellow jersey triumph is looming, but Geraint Thomas insists team orders will prevail when it comes to stopping rivals upsetting Team Sky's Tour de France victory plans.

With a 1min 39sec lead on four-time champion Chris Froome, Welshman Thomas is in prime position to add a maiden Tour de France victory to a growing collection of titles from the road and the track. But the former Olympic team pursuit champion has more than the Pyrenees mountains standing in his way over the final seven stages of the race.

Froome is team leader at Sky, owns six Grand Tour titles and can win a record-equalling fifth yellow jersey here. Team Sky principal Dave Brailsford may have key decisions to make in the coming seven stages, when Dutchman Tom Dumoulin, third at 1:50, will be looking for key allies in the Pyrenees mountains to help him dent Sky's hopes of a sixth victory from the past seven editions.

Thomas says the priority is to make sure Sky don't race against each other. "I've said it before, but it's the first time I've raced for three weeks, as a GC (general classification) leader so it's a bit of an unknown," said Thomas, after he and Froome trailed home over 18 minutes behind Spanish stage winner Omar Fraile in Mende. "We have a plan for the first Pyrenees stage, then for the next. "The main thing is we win there and we don't end up racing against each other and Dumoulin wins. "Then, we'd look really stupid."

After impressive back-to-back wins in two gruelling alpine stages, Thomas is on the form of his life -- leading to calls for Sky to give the Welshman their full backing. Yet his Grand Tour ambitions have often fell short. Sitting fourth overall in the 2015 Tour, where he helped Froome to his second yellow jersey, Thomas struggled on stage 19's climb to La Toussuire, losing 22 minutes and dropping to 15th overall. In last year's Giro d'Italia, won by Dumoulin, Thomas crashed out injured. And in last year's Tour de France the Welshman, having taken the yellow jersey on the opening stage, crashed out on stage nine while sitting second overall to Froome.

Thomas claims he is taking the challenge "day by day" safe in the knowledge that: "If something happens to me, we still have him (Froome) in the race." But the Welshman also has factors in his favour.

Froome, in his bid to become the first rider since deceased Italian great Marco Pantani, in 1998, to complete the Giro d'Italia-Tour de France double in the same year, won the Italian three-week race in June. Dumoulin was runner-up, and both he and Froome -- as many riders have in the past -- could pay for their Giro efforts over the coming days. Thomas added: "Dumoulin and Froomey have done the Giro, so you just don't know what will happen. "Anything can happen. Three big days in the Pyrenees to come plus a hard time trial. We'll see."

Asked if he felt Sky would prefer him to win instead of Kenyan-born Froome, Thomas joked: "For me, I'd be happier if I won obviously ! "Nah... I'm sure they'd be happier for either of us to win."