Froome leveraged an earlier attack from Team Sky team-mate Wout Poels. Over the following two kilometres, Poels drove the pace to help Froome put 28 seconds into Yates while Tom Dumoulin (Team Sunweb) and Domenico Pozzovivo (Bahrain-Merida) followed.
Maximilian Schachmann (Quick-Step Floors) won from the breakaway while the battle for the GC played out behind. Yataes now leads by just 28 seconds over 2017 race winner Dumoulin, 2-43 ahead of Pozzovivo and 3-22 ahead of Froome.
“[Yates] has been untouchable in this race so far, so it’s the first sign of any weakness that he showed so far,” Froome told Cycling Weekly after the stage.
“I had no idea that he was on the limit there. Only when I accelerated and turned around that I saw Pozzovivo and Dumoulin with me, but surprisingly not Simon.”
Froome has been on the back foot since day one of the 2018 Giro. He crashed in training ahead of the opening time trial in Jerusalem and again when the race was in Sicily – both times on his right side.
Watch: Giro d’Italia 2018 stage 18
Something seemed to be brewing when Team Sky sent Wout Poels up the road. That meant that Froome had a helper for an eventual move on the 13.9-kilometre climb in Italy’s northwest Piedmont region.
“That was something we decided to do on the last climb. Wout was feeling good and we agreed that he’d push on, and we’d see what would happen in the last few kilometres, if I could get across to him. It worked out really well actually,” Froome continued.
“I was just fallowing the wheels and I saw bit of an opportunity in the last kilometre or so just to push on a bit and test the waters. I didn’t expect Simon to be the one not able to follow wheels. That’s the first time in this race that he’s looked slightly vulnerable.”
Froome now has a realistic shot at the Giro d’Italia podium, 39 seconds behind Italian Domenico Pozzovivo. And if he continues with his upward trend and goes for a bold attack then he could perhaps even take the pink jersey.
Two high-mountain days through the Alps remain before the race transfers south to Rome for a flat stage on Sunday. Stage 19 climbs to the Jafferau ski station with the gravel Colle delle Finestre and Sestriere being tackled beforehand. Stage 20 finishes at Cervinia after two first category passes.
“I imagine that the other guys will have sensed weakness [in Yates] and it’ll make for some very explosive racing in these next days now,” Froome added.
“Let’s see, the race is still on. Two extremely hard days are coming up now, a pretty cool climb tomorrow with Colle delle Finestre. There’s still a lot to race for.”