Stage 1 winner Riley Sheehan was dropped inside the final kilometre, allowing August to turn the stage victory into the overall race lead as well.
INEOS finally make sustained control count
INEOS had been one of the dominant forces at the front for a second successive day. After helping control the Stage 1 break and then setting up Turner for the sprint in Karlovy Vary, they again took responsibility for much of the chase before the first summit finish of the race.
That work had gone unrewarded on Thursday when Sheehan came past Turner at the line. On Jested, however, INEOS kept numbers around August deep into the finale and this time finished the job.
The decisive phase of the stage was complicated several kilometres from the summit when around 15 riders crashed on the climb to Jested. Mikel Landa was the biggest-name casualty and was left struggling to regain contact as the front group continued towards the summit. Jakub Otruba, Kamiel Bonneu and Jan Castellon were also among the riders caught up in the incident, which split the race at a crucial point in the first major GC stage of the week.
With the crash behind them, INEOS continued to press on. Ben Turner worked deep into the climb before Haig and Svestad-Bardseng took over closer to the finish, keeping August in position for the final kilometre.
Sheehan, who had won the opening stage in Karlovy Vary and started the day in yellow, finally lost contact inside the final kilometre as the gradients bit. Landa was also visibly struggling by that point, while the remaining contenders prepared for the sprint to the line.
Fancellu was first to commit, but August had the stronger finish and came past to secure the stage win for INEOS. Pozzovivo crossed third, while August's victory and Sheehan's late loss of contact put the American into the race lead.
Schuran takes control of mountains classification
Earlier in the day, Gil Gelders, Mattia Bais, Michal Schuran and Martin Voltr formed the main breakaway after an aggressive opening from Mlada Boleslav. Schuran, who had already spent much of Stage 1 in the break, used the move to target the mountains classification. He took maximum points at both Vrchovany and Vyprez, moving clear of Pepijn Reinderink before eventually being dropped from the break on the approach to Jested.
Voltr had earlier won the intermediate sprint before losing contact on Vyprez, leaving Gelders and Bais as the final two escapees. Netcompany INEOS led much of the chase and brought the pair back as the peloton reached the foot of the final 15-kilometre climb.
TotalEnergies briefly took over for Jordan Jegat once the road tilted upwards, but the crash that followed changed the complexion of the finale and left INEOS best placed to control the run to the summit.
August made that work count at the line, turning two days of sustained INEOS control into both a stage victory and the yellow jersey after the team had missed out by one place in Karlovy Vary 24 hours earlier.