The Colombian finished fourth on the stage and sits in the same position on the general classification just 35 seconds off the blistering pace set by Stage 3 winner Remco Evenepoel on the summit finish of the nine-kilometre Picón Blanco climb.
But his form is no surprise to Mitchelton-Scott.
"If there's one guy in this team that has benefitted most from the lockdown, it's definitely Esteban," director Matt White told the earlier this month. "He's been able to string a lot of consistent training together at home in high altitude."
"He looks in super shape."
White reiterated this point to following Stage 3 as he also praised the equally impressive performance of his team who pushed the pace to chase down the break and put Chaves into a strong position by the middle of the climb.
"We saw this was a good race to prepare for goals in the future and if we hadn't chased when we did maybe they could have stayed away for the stage win," White told .
"So we took the race by the scruff of its neck and gave Esteban every chance for a stage result and he gave it a good try.
"Lockdown or not, you can see how hard people have been working, and Esteban has benefited from being in Colombia for nearly nine months now, and being able to work very hard at home."
“The team did a really awesome job today," Chaves said. "We raced like one unit and at the end we attacked from four kilometres to the finish line.
“At the start it was a question mark for everyone in the peloton about how it would be, but now everything is clearer and for Saturday’s final stage it will be different how everyone approaches the final climb.
“We are happy, as even in the crosswinds, we rode together like a real team and everybody did an awesome job.
White said 'realistically' 20-year-old Evenepoel would be hard to beat with just two stages remaining and the form he is in.
“But if we can move up one place onto the podium that would be a very good result and Esteban is very familiar with that final climb on the last day.”
The stage win was Evenepoel's fourth this season after winning the ITT at Vuelta a San Juan Internacional, and two stages at Volta ao Algarve, both stage races he also won overall.