"Why not?" Froome told Cycling Weekly ahead of the start of stage five when asked if he is the same rider we have seen win the Tour de France four times in the past.
"Physically? Yeah. All the numbers have been right where I'd want them, right were I'd expect them after all the training. Everything is on track in that respect."
Froome sits 55 seconds back in the general classification behind leader Rohan Dennis (BMC Racing). Dumoulin, who gained time on the short and steep Caltagirone finish, is only one second back, Simon Yates (Mitchelton-Scott) at 17, Thibaut Pinot (Groupama-FDJ) 34, Esteban Chaves (Mitchelton-Scott) 47, Michael Woods (EF Education First-Drapac) 53.
Watch: Giro d'Italia stage four highlights
The technical run-in to Caltagirone kicked up in the final 17 kilometres but Froome typically handles himself well in such finishes. Instead, Woods, Yates and Dumoulin slipped away.
"It was a tough day. It wasn't great to lose more time like that, especially on a stage like that," Froome continued.
"I had a bit of a run-in coming into that last kilometre. I was put into the barriers. I almost came to a dead stop and had to start again. That wasn't ideal, but that's bike racing. I have to get on with it now and hopefully that doesn't happen again. You have to look ahead now, look at where to get back time back."
The Giro d'Italia began with three stages in Israel, where Froome crashed in training ahead of the opening time trial. The race returned to Italy via Catania in Sicily but has yet to hit the mainland or the long mountain passes and summit finish stages of the third week.
Only on Thursday to Mount Etna and on Saturday to Montevergine di Mercogliano will the climbing really begin. It will be a taste of what is to come in the second half of the 2018 Giro and Froome may find space for revenge.
"Let's see how it goes. There are a lot of guys who want to get time back in the mountains and won't be relying on that time trial later on the race [the 34.2km time trial stage 16 to Rovereto]," said Froome. "I think we can see a very aggressive day of racing once we start hitting the longer mountains."
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