After a fast-paced ride through the Beaujolais vineyards Vingegaard is only 17 seconds clear of Pogacar in the overall standings ahead of three days in the mountains the Dane described as "decisive".
For Friday's French national holiday of July 14 the Tour has programmed a marquee mountain finish at the top of Le Grand Colombier in the Jura mountain range - a regular obstacle on recent Tours.
"Tomorrow will be a decisive day," Vingegaard said.
"It's a long, hard climb, it all comes down to who is feeling good and who is not," he added.
Pogacar, the Tour winner in 2020 and 2021, said: "I want to win it. It's a good climb, if I have the legs I'll attack. I should be good."
Pogacar added he wanted an early night ahead of the Grand Colombier.
On a lighter note Vingegaard admitted to enjoying a tipple in his free time when asked about the local wine as he dropped his often cagey approach to the press.
"My wife and I enjoy a bottle of wine from time to time but as a cyclist obviously not so often. Personally I prefer a bottle of white," he said.
Party time for Izagirre
It was a second win for Izagirre's team Cofidis after Victor Lafay triumphed in San Sebastian, and also a second Basque win after Pello Bilbao won stage 10 on Tuesday.
"It's great for the Basques, three stages there and two wins for us (the Basques)," Izagirre said.
"Tonight we're going to have a party," said the winner who will be far from alone with France preparing for its national holiday on Friday.
There was around 25km of climbing on the run from Roanne to Belleville as the peloton tore across the hilly route with the pack splintering.
Cutting an infernal pace, over 100 riders soon fell off as they pedalled through some of France's most prestigious vineyards.
An elite escape group formed only 80km from home and even this divided many times before the 34-year-old Izagirre made his decisive move on the fifth and toughest ascent, the Col de la Croix Rosier, a 5.3km-long stretch at eight percent gradient 28km from the finish.
Having won stages on all three Grand Tours Izagirre executed a ruthless finale, extending his lead all the way to the line in Belleville.
Frenchman Thibaut Pinot was part of the breakaway gaining over four minutes on the main contenders and climbing back into the top 10.
Belgian sprinter Jasper Philipsen had hoped for a quiet day in the peloton with the possibility of a bunch sprint where he could glean a fifth stage win but he did at least retain his huge lead in the green jersey standings.
Another fast man, Fabio Jakobsen of the Quick-Step team, withdrew from the Tour ahead of stage 12, struggling to shake off the after-effects of a hard fall.
"At this point it seems impossible for me to get to Paris," he explained.
Others might be persuaded of this impossibility if they take a close look at the road ahead.
Saturday ends with a sensational downhill ride from Les Portes du Soleil, while 24 hours later it should be a blockbuster climb at Saint-Gervais Mont Blanc.
