Lausanne - France's Pierre-Roger Latour claimed the Tour of Switzerland lead after Wednesday's testing fifth stage won by Darwin Atapuma.
Latour, riding for AG2R, snatched the yellow jersey from Peter Sagan with a third-place finish behind BMC's Colombian rider Atapuma and Warren Barguil (Giant).
The 126km run from Brig-Glis to Cari was the first of three mountain stages and featured three tough climbs, two of which were hors category.
And it proved a testing time for Sagan, Slovakia's 26-year-old world champion, who lost over 19 minutes to Latour, trailing in 70th.
Latour crossed the line seven seconds behind Atapuma at the end of the second of two hors category climbs up to the ski station at Cari.
Renowned climber Atapuma relished the mountainous terrain. He made his ultimately successful bid for stage glory six kilometres from the end.
In the overall standings Latour leads by a whisker from Lotto NL's Dutch rider Wilco Kelderman. Sky's Geraint Thomas is placed third, five seconds behind, with Barguil fourth, 16sec away.
Thursday's sixth stage is a 162.8km ride once again suiting the climbers in the peloton with the col du Klausen the day's toughest ascent with another climb to the finish at Amden.
Tour of Switzerland fifth stage results, a 126.4km ride from Brig to Car, on Wednesday:
1. Darwin Atapuma (COL/BMC) 3hr 41min 52sec, 2. Warren Barguil (FRA/GIA) at 0:04sec, 3. Pierre-Roger Latour (FRA/ALM) 0:07, 4. Tejay Van Garderen (USA/BMC) 0:09, 5. Wilco Kelderman (NED/LNL) 0:09, 6. Geraint Thomas (GBR/SKY) 0:12, 7. Andrew Talansky (USA/CAN) 0:12, 8. Rui Costa (POR/LAM) 0:16, 9. Michele Scarponi (ITA/AST) 0:16, 10. Miguel ngel Lpez (COL/AST) 0:16, 11. Simon Spilak (SLO/KAT) 0:32, 12. Jarlinson Pantano (COL/IAM) 0:32, 13. Gorka Izagirre (ESP/MOV) 0:36, 14. Vctor De la Parte (ESP/CCC) 0:43, 15. Jon Izagirre (ESP/MOV) 0:43, 16. Sergey Chernetsky (RUS/KAT) 0:59, 17. Tim Wellens (BEL/LOT) 1:05, 18. Jan Polanc (SLO/LAM) 1:14, 19. Pawel Cieslik (POL/VAT) 1:18, 20. Mathias Frank (SWI/IAM) 1:21
70. Peter Sagan (SVK/TIN) 19:46.
1. Pierre-Roger Latour (FRA/ALM) 18hr 04min 54sec, 2. Wilco Kelderman (NED/LNL) at 0:00, 3. Geraint Thomas (GBR/SKY) 0:05, 4. Warren Barguil (FRA/GIA) 0:16, 5. Tejay Van Garderen (USA/BMC) 0:18, 6. Andrew Talansky (USA/CAN) 0:19, 7. Gorka Izagirre (ESP/MOV) 0:27, 8. Jon Izagirre (ESP/MOV) 0:30, 9. Miguel Angel Lopez (COL/AST) 0:34, 10. Jarlinson Pantano (COL/IAM) 0:34, 11. Rui Costa (POR/LAM) 0:35, 12. Michele Scarponi (ITA/AST) 0:38, 13. Simon Spilak (SLO/KAT) 0:44, 14. Tim Wellens (BEL/LOT) 0:47, 15. Sergey Chernetsky (RUS/KAT) 1:06, 16. Mathias Frank (SWI/IAM) 1:38, 17. Petr Vakoc (CZE/ETI) 2:07, 18. Vasil Kiryienka (BLR/SKY) 2:16, 19. Darwin Atapuma (COL/BMC) 3:15, 20. Vctor De la Parte (ESP/CCC) 3:42