Stage 11 of the HTV Cup was a short crit stage in Huế, and with one of the key GC stages to follow, this being such a short stage the main protagonists were fairly quiet. The two Đồng Tháp teams, Domesco and Dopagan, worked to bring this to a sprint with the aim that Trần Tuấn Kiệt could pick up the blue jersey once more. In the end, however, this type of pan flat short stage was perfect for the previously out of sorts sprint specialist Lê Nguyệt Minh to break his duck for the year - he has countless wins in the race over the last few years, and it was very unusual to see him winless at this stage of the event. Dopagan succeeded in their aims as Trần Tuấn Kiệt took 2nd and with it the blue jersey, while Nguyễn Tấn Hoài moved to within 4 seconds of his teammate's GC lead with third place on the day.
Stage 12, however, was a key one for the race, only 113km in length but with three mountain passes including the biggest of the day, Đèo Hải Vân, just over 25km from the line. This had been where Javier Sardá would set off to try to set his GC aims in motion in the last few years, and so it proved for the replacement extranjeros this year. The break took the first mountain pass with those chasing with interest behind (led by Konstantin Nekrasov) just mistiming it and coming up short. On the second, đèo Phú Gia, the until-now-quiet Iranian Ali Khademi took the points ahead of Nekrasov, also the first major act of the race for his Gạo Hạt Ngọc Trời team, the sister of the dominant Lộc Trời squad.
When the riders hit Hải Vân, it was all systems go from the bottom. The number of major climbs in this year's edition is low (even the Đà Lạt stage is the weakest it's been since 2018, coming from the east rather than south east meaning the summits are further from the finish) so the riders knew this was going to be a crucial stage for the race. Over in Europe this would be a decent cat.2 kind of climb, 9km at 5% but with its first and last kilometres at 8% and a bit of a dip before that final kilometre. Võ Thanh An attacked pretty much as soon as the climb began, Nguyễn Phạm Quốc Khang and Konstantin Nekrasov set off in pursuit.
But then, Cosmonaut Frolov blasted off.
One by one, he chewed up and spat out the earlier moves and got himself solo at the front. Võ Thanh An fought gamely but you can't battle the space age. Loïc Désriac was battling on the front of the remains of the bunch, as days of controlling for the sprints had left Lộc Trời's domestiques gasping for air on the climb and their three-strong leadership group were forced to figure it out for themselves. Võ made it across the summit 42 seconds later in 2nd, but was clearly struggling compared to the Russian and Phan Hoàng Thái led the 15 or so riders remaining in the péloton across at around a minute back. On the way down a few stragglers got back on to the bunch but this only allowed Frolov to extend his advantage before Lộc Trời could get reinforcements, and they were clearly spent in the run-in; first Konstantin Nekrasov and then a small group of 5 broke off the front of the remainder of the group to steal a march at the line and also prevent Lộc Trời from negating any of their losses via time bonuses either. Nekrasov crossed the line 1'57 behind his countryman, and Nguyễn Hướng won the sprint for 3rd of his group, which the chasing bunch just managed to get close enough to be credited with the same time as, at 2'03.
Cosmonaut Frolov therefore now takes a commanding lead of 1'49" in the GC from outgoing yellow jersey Quàng Văn Cường, who also failed to regain the blue points jersey, though in some consolation Nguyễn Tấn Hoài regains it for the team. With neither being able to pick up any bonus seconds and Nekrasov's gains limited to 12" (6" on the road plus 6 bonus seconds) Lộc Trời hold 2nd and 3rd with the two durable fast men, but it's hard to see where they gain enough time on Frolov without the Russian making a mistake or suffering some misfortune.