Sky's British leader extended his lead by nearly one and a half minutes, from 2-27 to 3-52 on Dutchman Bauke Mollema (Trek-Segafredo) on Thursday in the mountain time trial to Megève.
"This point in the race, he physically looks as good as anybody, if not as strong as anybody," Brailsford said. "In cycling, though, anything can happen. The weather is going to turn by the sounds of it. We know in this sport that when the weather turns, anything can happen.
"You can't say the Tour is over, I'd like to say 'yes' but there's two difficult days to come. It was a violent effort today, so you don't know how everyone is going to back up now. We'll see how we go tomorrow."
It appears, however, that the real fight is behind Froome for second and third spot with the race leader holding such a comfortable margin.
Behind Mollema at 3-52, Brit Adam Yates (Orica-BikeExchange) is at 4-16, Nairo Quintana (Movistar) at 4-37 and Romain Bardet (AG2R La Mondiale) at 4-57.
"You never know, but normally, if he stays healthy, he'll for sure win the Tour de France," said Tom Dumoulin (Giant-Alpecin).
The Dutchman placed second behind Froome in today's stage and last year, he lost the Vuelta a España overall lead on the final mountain stage to Italian Fabio Aru (Astana).
"Mollema and Yates, they just need to try to follow and keep their podium spots.”
Yates, only 23-years-old, said that he is aiming to keep his third spot or move up to second overall.
"Chris Froome looks so strong in first place," Yates added. "He almost has four minutes with three stages to go, the win is probably out of the question."
Froome looked more comfortable than ever in this Tour or perhaps in any of the Tours he raced, including the victorious 2013 and 2015 editions. Today, he wore the yellow jersey for the 40th time in his career.
"The main thing here is just to stay safe," Froome said when asked if there was any way he could lose the race lead.
"I have a four-minute advantage. I have a great advantage, it's just about staying safe now over these next two days."
After the descent to Morzine, Froome only has to manage the final flat stage into Paris.
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