After Thomas was chased down by Sergio Higuita (Bora-Hansgrohe) and race leader Jakob Fuglsang (Israel-Premier Tech) in person, the Welshman placed eighth on the ultra-tough stage featuring two Hors-Categorie climbs.
Thomas is now just one second behind Fuglsang on GC and, after a winter he himself called "difficult" and an unremarkable first half of the season, it looks like Suisse could be marking a turning point in his year.
The Tour de France, too, is just around the corner, and although the 2018 Tour winner did not mention it in a post-stage interview in a week which has been fraught with off-race difficulties and incidents for the whole Tour de Suisse peloton, July must surely be on his mind as well.
"The week we've had, the altitude and heat, I think everyone was a little more cautious," Thomas said. "Everyone's a few men down but [teammate] Dani [Martínez] did an incredible job there."
After Martínez had worked hard on the final climb, Thomas tried to open up a gap, but as he said, a strong headwind made it all much more difficult.
"There wasn't much I could do, but I decided I'd sprint at the end - but that's just good training, isn't it?" Thomas said with his typical deadpan humour.
He agreed with reporters in any case that it was "nice to be back in the mix".
"For sure, everyone's had a few ups or downs, the winter was really bad for me, but it's nice to be back in the mix, whether it's doing lead-outs or riding for GC. Keep the body guessing!"
With Martínez having already lost time, and Adam Yates having left the race with COVID-19, Thomas finds himself as the sole leader at Ineos Grenadiers.
He said that while Saturday's second mountain stage has a harder final climb, the 12.8-kilometre Malbun, it would be difficult to predict what would happen. Sunday's final 25-kilometre time trial, he said, would inevitably be a different story.
"Tomorrow could be a little gap, or there could be splits. Either way there are two big days, for sure."
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Alasdair Fotheringham has been reporting on cycling since 1991. He has covered every Tour de France since 1992 bar one, as well as numerous other bike races of all shapes and sizes, ranging from the Olympic Games in 2008 to the now sadly defunct Subida a Urkiola hill climb in Spain. As well as working for Cyclingnews, he has also written for The Independent, The Guardian, ProCycling, The Express and Reuters.