Pavel Sivakov claimed Team Sky's second victory in a row at the Tour of the Alps to take the race lead from team-mate Tao Geoghegan Hart on stage two.
The Russian, 21, kicked away from Astana's Jan Hirt inside the final 300m to secure his first professional win in the 178.7km stage to Schenna, Italy.
Britain's Hart, 24, finished eighth on Tuesday to slip to seventh overall, 43 seconds down on Sivakov.
Team Sky leader Chris Froome lost one minute 34 seconds on the stage.
The four-time Tour de France champion, 33, lost contact with the group of favourites on the descent of the Jaufenpass and finished 17th.
Froome, who is is trying to hit top form in time for the start of his bid for a fifth Tour de France title on 6 July in Brussels, is now 14th overall, 1:44 back on Sivakov with three stages remaining.
Sivakov was one of eight riders to break clear on the descent before he attacked the group with 3.5km remaining.
Czech Hirt bridged across to Sivakov with 1.7km to go on a flat section but the highly-rated Sky rider had too much power on the final drag to the line, winning by four seconds, with Italy's Mattia Cattaneo third, 13 seconds further back.
Sivakov now leads Hirt by eight seconds in the general classification, with Cattaneo third at 23 seconds behind.
"We could not have wished for a better start to the race - two stages, two wins, it's unbelievable," said Sivakov.
"The favourites looked at Tao and I had the opportunity to go in the break.
"We have a really good young group and we work together really well."
Geoghegan Hart, who took his first senior win of his career on Monday, stuck with the favourites until a late attack by Vincenzo Nibali, but limited his losses to finish 13 seconds behind the Italian.
This will be the final stage race for Team Sky with their current sponsor. Ineos, a chemicals firm owned by Britain's richest man Sir Jim Ratcliffe, takes over for the Tour de Romandie, starting on 30 April.
Tour of the Alps - stage two result
1. Pavel Sivakov (Rus/Team Sky) 4hrs 58mins 17secs
2. Jan Hirt (Cze/Astana) +4secs
3. Mattia Cattaneo (Ita/Androni Giocattoli-Sidermec) +17secs
4. Fausto Masnada (Ita/Androni Giocattoli-Sidermec) +22secs
5. Hermann Pernsteiner (Aut/Bahrain-Merida) +29secs
6. Rafal Majka (Pol/Bora-Hansgrohe) Same time
7. Vincenzo Nibali (Ita/Bahrain-Merida)
8. Tao Geoghegan Hart (GB/Team Sky) +43secs
9. Pello Bilbao (Spa/Astana Pro Team) Same time
10. Nikita Stalnov (Kaz/Astana) +52secs
17. Chris Froome (GB/Team Sky) +1min 34 secs
General classification after stage two
1. Pavel Sivakov (Rus/Team Sky) 8hrs 28mins 55secs
2. Jan Hirt (Cze/Astana) +8secs
3. Mattia Cattaneo (Ita/Androni Giocattoli-Sidermec) +23ecs
4. Rafal Majka (Pol/Bora-Hansgrohe) +39secs
5. Hermann Pernsteiner (Aut/Bahrain-Merida) Same time
6. Vincenzo Nibali (Ita/Bahrain-Merida)
7. Tao Geoghegan Hart (GB/Team Sky) +43secs
8. Pello Bilbao (Spa/Astana Pro Team) +53secs
9. Nikita Stalnov (Kaz/Astana) +1min 02secs
10. Roland Thalmann (Swi/Team Vorarlberg Santic) +1min 08secs
14. Chris Froome (GB/Team Sky) +1min 44secs