Landa gained time on Aru and on his team-mate Chris Froome when he followed a move by Alberto Contador (Trek-Segafredo). The Italian in yellow saw it coming.
“For sure, he was a bit far behind so I knew he would try something today but I couldn’t follow everyone,” Aru said. “Now, considering where he is at on GC, I will give him less freedom.”
Landa jumped from seventh to fifth, cutting 1-46 into Aru’s overall lead. Aru, with an even weaker team now that Jakob Fuglsang abandoned with a fractured elbow and wrist, must keep an eye not only on three-time winner Froome, but also Landa.
The two raced two years together in Astana. In the 2015 Giro d’Italia, Landa worked for Aru, but when his leader suffered, he looked poised to take over and take on Contador. Aru rebounded, but Landa took home two mountain stages and a third place overall. Sky took notice and signed the Basque that off-season.
“Well for sure, I know Mikel Landa very well, he is a very strong rider, but it was a special stage today,” Aru continued. “Landa being three minutes down on GC this morning, the distance between us was bigger than it was in the cases of the other riders.
“Landa obviously had a good race, I don’t know how Team Sky will work that out later between Landa and Froome, but we will also worry about that later.”
Watch: Tour de France 2017 stage 13 highlights
Aru held his ground in the short 101-kilometre stage, the last this year in the Pyrenees. Besides Landa with his long-range move, only Daniel Martin (Quick-Step Floors) and Simon Yates (Orica-Scott) were able to make any ground. They gained nine seconds on the descent to Foix.
“I was expecting attacks from all of the riders and I followed, all of those who were closest to me on GC,” added Aru.
“Chris remains one of my direct rivals, because it is very tight. I was expecting Chris to attack in the last kilometres uphill, and he also attacked in the downhill.
“I looked at keeping under control those who were closest to me, so it was another very hard stage but I am happy with the way it went.”
Aru should hold the lead through stage 14, but will be under fire again in stage 15 on Sunday. If he keeps the famous yellow jersey or maillot jaune, the next test should come in the Galibier stage after the second rest day.